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Previous studies have shown a slowdown in the warming rate of the annual mean global surface temperature in the recent decade and it is referred to as the hiatus in global warming. Some recent studies have suggested that the hiatus in global warming is possibly due to strong cooling in the tropical Pacific. This study investigates the possible role of the Indian Ocean warming on the tropical Pacific cooling. Despite the continued rise in sea surface temperature (SST) over the tropical Indian Ocean, SST over the tropical Pacific has shown a cooling trend in the recent decade (2002 − 2012). It is well known fact that the Indian Ocean and the Pacific Ocean are strongly coupled to each other and the Indian Ocean basin wide warming is triggered by El Nino on interannual time scale. However, in the recent decade, this relationship is weakening. The recent Indian Ocean warming is triggering a Matsuno-Gill type response in the atmosphere by generating anomalous cyclonic circulations on either side of equator over the tropical Indian Ocean and anomalous easterlies along the tropical Pacific Ocean. These anomalous easterlies result in Ekman divergence in the equatorial Pacific and produce upwelling Kelvin waves, cools the tropical Pacific and therefore indirectly contributes to the hiatus in global warming.

The tropical Pacific cooling from the early 1990s to 2013 has contributed to the slowdown of globally averaged sea surface temperatures (SSTs). The origin of this regional cooling trend still remains elusive. Here we demonstrate that the remote impact of Atlantic SST anomalies, as well as local atmosphere-ocean interactions, contributed to the eastern Pacific cooling during this period. By assimilating observed three-dimensional Atlantic temperature and salinity anomalies into a coupled general circulation model, we are able to qualitatively reproduce the observed Pacific decadal trends of SST and sea level pressure (SLP), albeit with reduced amplitude. Although a major part of the Pacific SLP trend can be explained by equatorial Pacific SST forcing only, the origin of this low-frequency variability can be traced back further to the remote impacts of equatorial Atlantic and South Atlantic SST trends. Atlantic SST impacts on the atmospheric circulation can also be detected for the Northeastern Pacific, thus providing a linkage between Atlantic climate and Western North American drought conditions.

As the recent global warming hiatus has attracted worldwide attention, we examined the robustness of the warming hiatus in China and the related dynamical mechanisms in this study. Based on the results confirmed by the multiple data and trend analysis methods, we found that the annual mean temperature in China had a cooling trend during the recent global warming hiatus period, which suggested a robust warming hiatus in China. The warming hiatus in China was dominated by the cooling trend in the cold season, which was mainly induced by the more frequent and enhanced extreme-cold events. By examining the variability of the temperature over different time scales, we found the recent warming hiatus was mainly associated with a downward change of decadal variability, which counteracted the background warming trend. Decadal variability was also much greater in the cold season than in the warm season, and also contributed the most to the previous accelerated warming. We found that the previous accelerated warming and the recent warming hiatus, and the decadal variability of temperature in China were connected to changes in atmospheric circulation. There were opposite circulation changes during these two periods. The westerly winds from the low to the high troposphere over the north of China all enhanced during the previous accelerated warming period, while it weakened during the recent hiatus. The enhanced westerly winds suppressed the invasion of cold air from the Arctic and vice versa. Less frequent atmospheric blocking during the accelerated warming period and more frequent blocking during the recent warming hiatus confirmed this hypothesis. Furthermore, variation in the Siberian High and East Asian winter monsoon season supports the given conclusions.

During the global warming hiatus period (1998–present), a pronounced increase in the number of intense typhoon occurrences was identified over the Philippine Sea (PS: 5°–25°N, 125°–140°E) in September after the mid-2000s. Comparing two periods before and after the mid-2000s indicates that intense typhoons rarely occurred over the PS in September before the mid-2000s, with a frequency of fewer than 0.4 per year, but reached up to nearly 1.5 per year after the mid-2000s. The abrupt increase in intense typhoon occurrences over the PS was primarily attributed to increased tropical cyclone (TC) genesis and favorable large-scale conditions for TC intensification. The increase in TC genesis number over the PS was caused by contributory dynamical conditions, including positive low-level relative vorticity anomalies and anomalous ascents, which corresponded to a southwestward shift and strengthening of the monsoon trough. In addition, among the favorable large-scale conditions, the increased relative humidity that resulted from intensified moisture flux convergence exerted essential effect on the TC intensification. These changes in atmospheric environmental conditions favoring intense typhoon occurrences over the PS were primarily associated with the change in the tropical Indo-Pacific sea surface temperature (SST) around the mid-2000s. Besides that, the positive feedback TCs exerted on the circulation was also conducive to the unusual growth in intense typhoon occurrences over the PS. And note that the role of SST anomalies in the air–sea interaction is the key to interpret why the unique phenomenon only occurred in September.

Employing their newly proposed interannual difference method (IADM), Liu et al. (2009) and Shiu et al. (2012) reported a shocking increase of around 100% K−1 in heavy precipitation with warming global temperature in 1979–2007. Such increase is alarming and prompts us to probe into the IADM. In this study, both analytical derivations and numerical analyses demonstrate that IADM provides no additional information to that of the conventional linear regression, and also, it may give a false indication of dependence. For clarity and simplicity, we therefore recommend linear regression analysis over the IADM for the detection of dependence. We also find that heavy precipitation decreased during the global warming hiatus, and the precipitation dependence on temperature drops by almost 50% when the study period is extended to 1979–2014 and it may keep dropping in the near future. The risk of having heavy precipitation under warming global temperature may have been overestimated.

Based on three global annual mean surface temperature time series and three Chinese annual mean surface air temperature time series, climate change trends on multiple timescales are analyzed by using the trend estimation method of multi-sliding time windows. The results are used to discuss the so-called global-warming hiatus during 1998–2012. It is demonstrated that different beginning and end times have an obvious effect on the results of the trend estimation, and the implications are particularly large when using a short window. The global-warming hiatus during 1998–2012 is the result of viewing temperature series on short timescales; and the events similar to it, or the events with even cold tendencies, have actually occurred many times in history. Therefore, the global-warming hiatus is likely to be a periodical feature of the long-term temperature change. It mainly reflects the decadal variability of temperature, and such a phenomenon in the short term does not alter the overall warming trend in the long term.

Prior to the 2000s, the North Atlantic was the basin showing the greatest warming. However, since the mid-2000s during the so-called global warming hiatus, large amounts of heat were transferred in this basin from upper to deeper levels while the dominance in terms of atmospheric heat capture moved into the Indo-Pacific. Here we show that a large transformation of modal waters in the eastern North Atlantic (ENA) played a crucial role in such contrasting behavior. First, strong winter mixing in 2005 transformed ENA modal waters into a much saltier, warmer, and denser variety, transferring upper ocean heat and salt gained slowly over time to deeper layers. The new denser waters also altered the zonal dynamic height gradient reversing the southward regional flow and enhancing the access of saltier southern waters to higher latitudes. Then, the excess salinity in northern regions favored additional heat injection through deep convection events in later years.

Global mean surface temperature (GMST) rising has slowed down since late 1990s, which is referred to as the global warming hiatus. There was another global warming hiatus event during 1940s–1960s. The roles of the external forcing and the natural variability in both global warming hiatuses are explored, using EOF analysis. The first two leading EOF modes of the 5-year running mean global sea surface temperature (SST) reflect the global warming scenario (EOF1) and the interdecadal Pacific oscillation (IPO)-like natural variability (EOF2), respectively. In observation, PC2 was in its positive phase (eastern Pacific cooling) during 1940s–1960s, which contributed to the previous warming hiatus. In addition, GMST trends are found to be negative during late 1950s and 1960s in most of the CMIP5 historical runs, which implies that the external forcing also contributed to the pause in the GMST rising. It is further demonstrated that it is the natural radiative forcing (volcanic forcing) that caused the drop-down of GMST in 1960s. The current global warming hiatus has been attributed to the eastern Pacific cooling/enhanced Pacific trade winds. It is shown that the PC2 switched to its positive phase in late 1990s, and hence the IPO-like natural variability made a contribution to the slowdown of GMST rising in the past decade. It is also found that the EOF1 mode (global warming mode) of the observed SST features a smaller warming in tropical Pacific compared to the Indian Ocean and the tropical Atlantic. Such inter-basin warming contrast, which is attributed to the “ocean thermostat” mechanism, has been suggested to contribute to the intensification of Pacific trade winds since late 1990s as well. Global warming hiatuses are also found in the future projections from CMIP5 models, and the spatial pattern of the SST trends during the warming-hiatus periods exhibits an IPO-like pattern, which resembles the observed SST trends since late 1990s.

We investigate changes in daily precipitation extremes using Tropical Rainfall Measuring Mission (TRMM) data (1998-2013), which coincides with the "global warming hiatus." Results show a change in probability distribution functions of local precipitation events (LPEs) during this period consistent with previous global warming studies, indicating increasing contrast between wet and dry extremes, with more intense LPE, less moderate LPE, and more dry (no rain) days globally. Analyses for land and ocean separately reveal more complex and nuanced changes over land, characterized by a strong positive trend (+12.0% per decade, 99% confidence level (c.l.)) in frequency of extreme LPEs over the Northern Hemisphere extratropics during the wet season but a negative global trend (−6.6% per decade, 95% c.l.) during the dry season. A significant global drying trend (3.2% per decade, 99% c.l.) over land is also found during the dry season. Regions of pronounced increased dry events include western and central U.S., northeastern Asia, and Southern Europe/Mediterranean.

As climate change has occurred over east Asia since the 1950s, intense interest and debate have arisen concerning the contribution of human activities to the observed warming in past decades. In this study, we investigate regional surface temperature change during the boreal cold season using a recently developed methodology that can successfully identify and separate the dynamically induced temperature (DIT) and radiatively forced temperature (RFT) changes in raw surface air temperature (SAT) data. For regional averages, DIT and RFT contribute 44 and 56 % to the SAT over east Asia, respectively. The DIT changes dominate the SAT decadal variability and are mainly determined by internal climate variability, represented by the North Atlantic Oscillation (NAO), Pacific Decadal Oscillation (PDO), and Atlantic Multi-decadal Oscillation (AMO). Radiatively forced SAT changes have made a major contribution to the global-scale warming trend and the regional-scale enhanced semi-arid warming (ESAW). Such enhanced warming is also found in radiatively forced daily maximum and minimum SAT. The long-term global-mean SAT warming trend is mainly related to radiative forcing produced by global well-mixed greenhouse gases. The regional anthropogenic radiative forcing, however, caused the enhanced warming in the semi-arid region, which may be closely associated with local human activities. Finally, the relationship between the so-called "global warming hiatus" and regional enhanced warming is discussed.

Whether there is an obvious “hiatus” of warming at the global or regional scale is an outstanding issue, which has attracted worldwide attention. To investigate the response of temperature variation to global warming in Northeast China, it is necessary to reanalyze whether the regional warming trend has slowed down. Heilongjiang Province, located in the cold region in Northeast China, was selected as the study area. Based on the meteorological data recorded at 26 meteorological stations from 1960 to 2015, the spatiotemporal characteristics of temperature in this region were analyzed using the Mann-Kendall trend analysis, Sen's slope method and inverse distance weighting (IDW) method, and then compared with the temperature variations of the globe and mainland China. Furthermore, the cross wavelet method was applied to explore the teleconnection between temperature and large-scale climate patterns to investigate possible causes of temperature variations of this region. The results demonstrated that: 1) the spatial distribution of temperature showed latitudinal variations, and annual and seasonal temperatures showed warming trends, among which the warming trend in autumn was the most significant and the variation range in winter was the greatest. 2) In term of net temperature, global warming might have greater impacts over the central, western and northwestern parts of Heilongjiang Province. 3) Compared to the temperature variations of the globe and mainland China, hiatus phenomenon was detected in Northeast China, for there was an obvious cooling trend in spring. 4) Arctic oscillation (AO) was a key factor affecting the temperature change in this cold region and Pacific decadal oscillation (PDO) could be another closely-related climatic factor contributed to this hiatus period.

Widespread public and scientific interest in the recent global warming hiatus and related multidecadal climate variability stimulated a surge in our understanding of key metrics of global climate change. While seeking explanations for the nearly steady global mean temperature from late 1990s through the early 2010s, the scientific community also grappled with concomitant and seemingly inconsistent changes in other metrics. For example, over that period, Arctic sea ice experienced a rapid decline but Antarctic sea ice expanded slightly, summertime warm extremes continued to rise without evidence of a pause, and the expanding Hadley cell trend maintained its course. In this article, we review recent advances in understanding the multidecadal variability of these metrics of global climate change, focusing on how internal multidecadal variability may reconcile differences between projected and recently observed trends and apparent inconsistencies between recent trends in some metrics. We emphasize that the impacts of global scale, naturally occurring patterns on multidecadal timescales, most notably the Pacific and Atlantic Multidecadal Variability, tend to be more regionally heterogeneous than those of radiatively forced change, which weakens the relationship between local climate impacts and global mean temperature on multidecadal timescales. We conclude this review with a summary of current challenges and opportunities for progress.

The Mascarene High (MH) is a semi-permanent subtropical high-pressure zone in the South Indian Ocean. Apart from its large influence on African and Australian weather patterns, it also helps in driving the inter-hemispheric circulation between the Indian Ocean in the south and subcontinental landmass in the north. Using observations and reanalysis products, this study for the first time investigates recent warming trend observed in the MH region during the Global Warming Hiatus (GWH) period (1998-2016). Significant positive trends are observed in sea surface temperature (SST), sea surface height (SSH) and oceanic heat content (OHC) during this period in the MH region. Mixed layer heat budget analysis reveals the dominant role of heat advection in the observed warming trend. During the GWH period, stronger zonal currents advect the warm waters from the Western Pacific (WP) towards the MH region via the Indonesian Throughflow (ITF). This warming in the MH reduces the sea level pressure therein and establishes a weak pressure gradient between the MH and the northern hemisphere landmass. This in-turn weakens the cross-equatorial winds in the western Indian Ocean.

Long-term trends in global sea spray aerosol (SSA) emissions and dimethyl sulfide (DMS) fluxes from sea to air during the recent global warming hiatus (2000–2015) were analyzed using satellite observations and modelling data. The SSA emissions were estimated using a widely used whitecap method with sea surface temperature (SST) dependence. In addition, sea-to-air DMS fluxes were also used to quantify the secondary contributions of DMS through its sequential oxidation and gas-to-particle conversion. Aerosol optical depth (AOD) was estimated by an aerosol optical model using the number concentration of SSA and non-sea-salt sulfate from DMS. The estimated AOD, which was derived from the SSA and DMS emitted from the sea surface, was compared with satellite-derived AOD to quantify its (primary and secondary) contribution to atmospheric aerosol loading (i.e., observed AOD). Yearly global mean anomalies in DMS fluxes and AOD derived from SSA showed statistically significant downward trends during the recent global warming hiatus, whereas SSA emissions and AOD derived from DMS oxidation did not. In terms of regional trends, the decreases in SSA emissions during 2000–2015 occurred over the central Pacific Ocean, the Indian Ocean, and the Caribbean Sea, whereas upward trends in SSA emissions occurred over the tropical southeastern Pacific Ocean, the Southern Ocean, and the North Atlantic Ocean. DMS fluxes during the study period showed a clear downward trend over most regions of the global ocean. The estimates of the contributions of SSA (primary) and DMS (secondary) to atmospheric aerosol loading were 23–62% and 26–38%, respectively, with the largest primary contribution (~90%) over the Southern Ocean.

The slowdown in global warming since 1998, often termed the global warming hiatus. Reconciling the “hiatus” is a main focus in the 2013 climate change conference. Accurately characterizing the spatiotemporal trends in surface air temperature (SAT) is helps to better understand the “hiatus” during the period. This article presents a satellite-based regional warming simulation to diagnose the “hiatus” for 2001–2015 in China. Results show that the rapid warming is mainly in western and southern China, such as Yunnan (mean ± standard deviation: 0.39 ± 0.26 °C (10 yr)−1), Tibet (0.22 ± 0.25 °C (10 yr)−1), Taiwan (0.21 ± 0.25 °C (10 yr)−1), and Sichuan (0.19 ± 0.25 °C (10 yr)−1). On the contrary, there is a cooling trend by 0.29 ± 0.26 °C (10 yr)−1 in northern China during the recent 15 yr, where a warming rate about 0.38 ± 0.11 °C (10 yr)−1 happened for 1960–2000. Overall, satellite simulation shows that the warming rate is reduced to −0.02 °C (10 yr)−1. The changes in underlying surface, Earth's orbit, solar radiation and atmospheric counter radiation (USEOSRACR) cause China's temperature rise about 0.02 °C (10 yr)−1. A combination of greenhouse gases (GHGs) and other natural forcing (ONAT, predominately volcanic activity, and atmosphere and ocean circulation) explain another part of temperature trend by approximately −0.04 °C (10 yr)−1. We conclude that there is a regional warming hiatus, a pause or a slowdown in China, and imply that GHGs-induced warming is suppressed by ONAT in the early 21st century.

The recent global warming hiatus (GWH) was characterized by a La Niña–like cooling in the tropical Eastern Pacific accompanied with the Indian Ocean and the tropical Atlantic Ocean warming. Here we show that the recent GWH contributed significantly to the increased occurrence of intense tropical cyclones in the coastal regions along East Asia since 1998. The GWH associated sea surface temperature anomalies triggered a pair of anomalous cyclonic and anticyclonic circulations and equatorial easterly anomalies over the Northwest Pacific, which favored TC genesis and intensification over the western Northwest Pacific but suppressed TC genesis and intensification over the southeastern Northwest Pacific due to increased vertical wind shear and anticyclonic circulation anomalies. Results from atmospheric general circulation model experiments demonstrate that the Pacific La Niña–like cooling dominated the Indian Ocean and the tropical Atlantic Ocean warming in contributing to the observed GWH-related anomalous atmospheric circulation over the Northwest Pacific.

In recent decades, global warming hiatus/slowdown has attracted considerable attention and has been strongly debated. Many studies suggested that the Arctic is undergoing rapid warming and significantly contributes to a continual global warming trend rather than a hiatus. In this study, we evaluated the climate changes of Ny-Alesund, Svalbard, a representative location of the northern North Atlantic sector of the Arctic, based on observational records from 1975–2014. The results showed that the annual warming rate was four times higher than the global mean (+0.76 °C·decade−1) and was also much greater than Arctic average. Additionally, the warming trend of Ny-Alesund started to slow down since 2005–2006, and our estimates showed that there is a 8–9 years-lagged, but significant, correlation between records of Ny-Alesund and global HadCRUT4 datasets. This finding indicates that the Arctic was likely experiencing a hiatus pattern, which just appeared later than the low-mid latitudes due to transport processes of atmospheric circulations and ocean currents, heat storage effect of cryospheric components, multidecadal variability of Arctic cyclone activities, etc. This case study provides a new perspective on the global warming hiatus/slowdown debate.

Local precipitation variations in the context of global warming are a hot topic in the climate change research community. Using daily precipitation data spanning from 1984 to 2014 from 25 meteorological stations, the spatiotemporal variations of precipitation were analyzed for the southern part of Heihe River Basin (HRB), which is the second-largest inland river basin in Northwest China. Linear trend analysis, empirical orthogonal function (EOF) analysis, the Mann–Kendall test, and the moving t-test were employed in the study. Results showed that the regional annual precipitation exhibited an increasing trend with a slope of 13.1 mm per decade from 1984 to 2014. The increasing trend was detected at 21 sites and the first EOF illustrating the regional increasing trend explained 51.8% of the total variance. The increasing trend of annual precipitation was mainly due to an increase in autumn precipitation, while summer precipitation exhibited a weak declining trend and spring–winter precipitation remained unchanged. Moreover, the increasing precipitation trend was mainly caused by an abrupt increase around 1997, when the global warming hiatus occurred. Through 1997, the atmospheric circulation and physical structure, such as vertical upward motion, vapor transmission, and its convergence changed to be more favorable for precipitation in autumn, but unfavorable for precipitation in summer in the HRB.

Understanding multi-decadal variability is an essential goal of climate dynamics. For example, the recent phenomenon referred to as the "global warming hiatus" may reflect a coupling to an intrinsic, pre-industrial, multi-decadal variability process. Here, using a multi-fractal time series method, we demonstrate that forty-two data sets of seventy-nine proxies with global coverage exhibit pink noise characteristics on multi-decadal time scales. To quantify the persistence of this behavior, we examine high-resolution ice core and speleothem data to find pink noise in both pre- and post-industrial periods. We examine the spatial structure with Empirical Orthogonal Function (EOF) analysis of the monthly-averaged surface temperature from 1901 to 2012. The first mode clearly shows the distribution of ocean heat flux sinks located in the eastern Pacific and the Southern Ocean, and has pink noise characteristics on a multi-decadal time-scale. We hypothesize that this pink noise multi-decadal spatial mode may resonate with externally-driven greenhouse gas forcing, driving large-scale climate processes.

Throughout Chinese history, never have we been so aware of the importance of oceans today, nor have we ever been so close to becoming a maritime power. Ocean researchers like us should have the sense of responsibility as well the confidence to take on historical tasks trusted upon us in this crucial time of China’s ocean strategy development. Today, I’d like to talk about oceans on the following four subjects.

International audience; Two large ensembles (LEs) of historical climate simulations are used to compare how various statistical methods estimate the sea surface temperature (SST) changes due to anthropogenic and other external forcing, and how their removal affects the internally generated Atlantic multidecadal oscillation (AMO), Pacific decadal oscillation (PDO), and the SST footprint of the Atlantic meridional overturning circulation (AMOC). Removing the forced SST signal by subtracting the global mean SST (GM) or a linear regression on it (REGR) leads to large errors in the Pacific. Multidimensional ensemble empirical mode decomposition (MEEMD) and quadratic detrending only efficiently remove the forced SST signal in one LE, and cannot separate the short-term response to volcanic eruptions from natural SST variations. Removing a linear trend works poorly. Two methods based on linear inverse modeling (LIM), one where the leading LIM mode represents the forced signal and another using an optimal perturbation filter (LIMopt), perform consistently well. However, the first two LIM modes are sometimes needed to represent the forced signal, so the more robust LIMopt is recommended. In both LEs, the natural AMO variability seems largely driven by the AMOC in the subpolar North Atlantic, but not in the subtropics and tropics, and the scatter in the AMOC–AMO correlation is large between individual ensemble members. In three observational SST reconstructions for 1900–2015, linear and quadratic detrending, MEEMD, and GM yield somewhat different AMO behavior, and REGR yields smaller PDO amplitudes. Based on LIMopt, only about 30% of the AMO variability is internally generated, as opposed to more than 90% for the PDO. The natural SST variability contribution to global warming hiatus is discussed.

The issue of the global climate change as well as the climate change in China is of increasingly great concern for various governments, scientific and technological communities and public. Among them, the climate change evidence, mechanism and attribution, climate change impact, as well as climate change prediction and projection have been studied intensively in China. The present paper will concisely review and assess contributions and achievement made by Chinese scientists from the international perspective, which include the following six aspects: (1) the characters tics of regional surface air temperature and tropospheric temperature in China have shown significant increasing trends. The warming rate of the surface temperature is about 1.2℃ per hundred year with its uncertainty ranging of 0.9–1.52℃. (2) The researches of water cycle have indicated that regional precipitation change has had no obvious trend at a hundred-year scale. However, the precipitation pattern has changed since 1970s with more precipitation in western China, whereas in eastern China the pattern of “drought in North and flood in South” has been observed. The annual surface humidity has taken on increasing trend. Both the small pan evaporation and potential evaporation have appeared decreasing trends. The annual runoff of most rivers in eastern China has shown decreasing trends, while that in western China has shown increasing trends. (3) It is indicated that the anthropogenic forcing has produced significant effect on the long-term variation of the East Asian monsoon. The intensity of the East Asian summer monsoon will become stronger and the monsoonal rain belt will migrate northward. (4) The sea level has been affected by the global warming. Since 1980, the rising rate of sea level in China is about 2.9 mm/a, being higher than that of the global mean. (5) The attribution of the climate change has suggested that the surface temperature variation for the last 100 years is the result of the superimposition between the global warming and the natural Pacific Decadal Oscillation (PDO) or other oceanic phenomena. The fast warming rate and the intensity as well as the frequency of some extreme events (such as heat waves) in china are consistent with the global counterparts, mainly influenced by the increase of the green-house gases. (6) The model projections have stated that by the end of 21st century, the global surface temperature will possibly increase by 1.0–3.7℃. The increasing amplitude of surface temperature in China will be 1.3–5.0℃. The precipitation will increase by 5%–14% and the extreme events will more frequently occur.

Closure of the Earth’s energy budget relies on strong aerosol cooling since 1998, if the same feedbacks apply for anthropogenic and natural variability. An analysis of climate model simulations suggests that these feedbacks are instead distinct.

On the basis of mean temperature, maximum temperature and minimum temperature from the updated China Homogenized Historical Temperature Data Sets, the recent warming in the Tibetan Plateau (TP) during 1961–2005 and global warming hiatus period are examined. During 1961–2005, the mean temperature, maximum temperature and minimum temperature in the whole TP show a statistically increasing trend especially after the 1980s, with the annual rates of 0.27, 0.19 and 0.36 °C decade−1, respectively. The performance of 26 general circulation models (GCMs) available in the fifth phase of the Coupled Model Intercomparison Project (CMIP5) is evaluated in the TP by comparison with the observations during 1961–2005. Most CMIP5 GCMs can capture the decadal variations of the observed mean temperature, maximum temperature and minimum temperature, and have significant positive correlations with observations (R > 0.5), with root mean squared error

Equatorial Pacific changes during the transition from a nonhiatus period (pre-1999) to the present global warming hiatus period (post-1999) are identified using a combination of reanalysis and observed data sets. Results show increased surface wind forcing has excited significant changes in wind-driven circulation. Over the last two decades, the core of the Equatorial Undercurrent intensified at a rate of 6.9 cm s−1 decade−1. Similarly, equatorial upwelling associated with the shallow meridional overturning circulation increased at a rate of 2.0 × 10−4 cm s−1 decade−1 in the central Pacific. Further, a seasonal dependence is identified in the sea surface temperature trends and in subsurface dynamics. Seasonal variations are evident in reversals of equatorial surface flow trends, changes in subsurface circulation, and seasonal deepening/shoaling of the thermocline. Anomalous westward surface flow drives cold-water zonal advection from November to February, leading to surface cooling from December through May. Conversely, eastward surface current anomalies in June–July drive warm-water zonal advection producing surface warming from July to November. An improved dynamical understanding of how the tropical Pacific Ocean responds during transitions into hiatus events, including its seasonal structure, may help to improve future predictability of decadal climate variations.

The dominant modes of variability in the temperature and ocean heat content (OHC; 0–1000 m) of the central Labrador Sea were investigated using the Hilbert–Huang Transform (HHT) based on Argo profiles collected during 2003–2012. Warming trends of approximately 0.03°Cyr−1 were observed in the upper 2000 m of the water column. A strong annual temperature cycle exists and dominates at the 500 m depth, while signals at the interannual timescales can explain most of the temperature variability at the 1000 m and 1500 m depths. These interannual signals are closely correlated to the variability of deep convection in the Labrador Sea, which has intermittent enhancement of mixed layer depth (MLD)>1500 m. The Hilbert spectrum from the OHC in the Labrador Sea interior reveals two important components at frequencies of 0.8−1.2cycleyr−1 (T =0.8–1.25 years) and 0.1−0.3cycleyr−1 (T=3.3–10 years), respectively, superimposed on the warming trends. The former corresponds to the dominant seasonal cycle due to surface heating, while the latter is concomitant with the timing of the reoccurrence of convective events. We also found that the cumulative North Atlantic Oscillation (NAO) index significantly correlates to the low-frequency OHC variations. Therefore, the interannual signals in the Labrador Sea at especially the intermediate layers are attributed to changes in the deep convective processes and the atmospheric conditions. By comparing with an extended OHC record (1945–2010), it was further shown that the warming trends obtained from the 10-year Argo record are part of multi-decadal variations that presumably reflect the Atlantic Multi-decadal Oscillation (AMO). In addition, the recent OHC changes in the Labrador Sea (i.e., increased heat in the deeper layers) may be related to the current global warming hiatus, suggesting the potential contributions from the Atlantic Meridional Overturning Circulation (AMOC) to the low-frequency OHC in the Labrador Sea.

The spatial and temporal variability of the recent land warming hiatus have seldom been explored, despite their importance for understanding the mechanisms underlying the phenomenon. In this study, we applied piecewise linear regression to investigate the spatiotemporal patterns of the breakpoint time of warming over 40 years (1974–2013). Our results showed that at the global scale, mean annual temperature (MAT) over the land increased significantly until 2005 and that the warming trend then stalled. However, the breakpoint time of the warming varied greatly among different seasons and continents. We found no statistically significant breakpoint in MAT over the Northern Hemisphere, but MAT over the Southern Hemisphere showed a significant breakpoint (P

Recent global warming hiatus has received much attention; however, a robust and quantitative definition for the hiatus is still lacking. Recent studies by Scafetta, Wu et al., and Tung and Zhou showed that multidecadal variability (MDV) is responsible for the multidecadal accelerated warming and hiatuses in historical global-mean surface temperature (GMST) records, though MDV itself has not received sufficient attention thus far. Here, the authors introduce four key episodes in GMST evolution, according to different phases of the MDV extracted by the ensemble empirical-mode decomposition method from the ensemble HadCRUT4 monthly GMST time series. The “warming (cooling) hiatus” and “typical warming (cooling)” periods are defined as the 95% confidence intervals for the locations of local MDV maxima (minima) and of their derivatives, respectively. Since 1850, the warming hiatuses, cooling hiatuses, and typical warming have already occurred three times and the typical cooling has occurred twice. At present, the MDV is in its third warming-hiatus period, which started in 2012 and would last until 2017, followed by a 30-yr cooling episode, while the trend will sustain the current steady growth in the next 50 years. Their superposition presents steplike rising since 1850. It is currently ascending a new height and will stay there until the next warming phase of the MDV carries it higher.

Walking back talk of the end of warming Previous analyses of global temperature trends during the first decade of the 21st century seemed to indicate that warming had stalled. This allowed critics of the idea of global warming to claim that concern about climate change was misplaced. Karl et al. now show that temperatures did not plateau as thought and that the supposed warming “hiatus” is just an artifact of earlier analyses. Warming has continued at a pace similar to that of the last half of the 20th century, and the slowdown was just an illusion. Science , this issue p. 1469

The recent hiatus in global warming is likely to be reflected in Andean temperature, given its close dependence on tropical Pacific sea surface temperature (SST). While recent work in the subtropical Andes has indeed documented a cooling along coastal areas, trends in the tropical Andes show continued warming. Here we analyze spatiotemporal temperature variability along the western side of the Andes with a dense station network updated to 2010 and investigate its linkages to tropical Pacific modes of variability. Results indicate that the warming in tropical latitudes has come to a halt and that the subtropical regions continue to experience cooling. Trends, however, are highly dependent on elevation. While coastal regions experience cooling, higher elevations continue to warm. The coastal cooling is consistent with the observed Pacific Decadal Oscillation (PDO) fingerprint and can be accurately simulated using a simple PDO-analog model. Much of the PDO imprint is modulated and transmitted through adjustments in coastal SST off western South America. At inland and higher-elevation locations, however, temperature trends start to diverge from this PDO-analog model in the late 1980s and have by now emerged above the 1σ model spread. Future warming at higher elevation is likely and will contribute to further vertical stratification of atmospheric temperature trends. In coastal locations, future warming or cooling will depend on the potential future intensification of the South Pacific anticyclone but also on continued temperature dependence on the state of the PDO.

Portions of western North America have experienced prolonged drought over the last decade. This drought has occurred at the same time as the global warming hiatus—a decadal period with little increase in global mean surface temperature. Climate models and observational analyses are used to clarify the dual role of recent tropical Pacific changes in driving both the global warming hiatus and North American drought. When observed tropical Pacific wind stress anomalies are inserted into coupled models, the simulations produce persistent negative sea surface temperature anomalies in the eastern tropical Pacific, a hiatus in global warming, and drought over North America driven by SST-induced atmospheric circulation anomalies. In the simulations herein the tropical wind anomalies account for 92% of the simulated North American drought during the recent decade, with 8% from anthropogenic radiative forcing changes. This suggests that anthropogenic radiative forcing is not the dominant driver of the current drought, unless the wind changes themselves are driven by anthropogenic radiative forcing. The anomalous tropical winds could also originate from coupled interactions in the tropical Pacific or from forcing outside the tropical Pacific. The model experiments suggest that if the tropical winds were to return to climatological conditions, then the recent tendency toward North American drought would diminish. Alternatively, if the anomalous tropical winds were to persist, then the impact on North American drought would continue; however, the impact of the enhanced Pacific easterlies on global temperature diminishes after a decade or two due to a surface reemergence of warmer water that was initially subducted into the ocean interior.

This study investigates global surface temperature data since 1920, and the Interdecadal Pacific Oscillation is found to be largely responsible for temperature fluctuations, exhibiting different spatial patterns to anthropogenic temperature drivers.

Estimating the thermal information in the subsurface and deeper ocean from satellite measurements over large basin-wide scale is important but also challenging. This paper proposes a support vector machine (SVM) method to estimate subsurface temperature anomaly (STA) in the Indian Ocean from a suite of satellite remote sensing measurements including sea surface temperature anomaly (SSTA), sea surface height anomaly (SSHA), and sea surface salinity anomaly (SSSA). The SVM estimation of STA features the inclusion of in-situ Argo STA data for training and testing. SVM, one of the most popular machine learning methods, can well estimate the STA in the upper 1000 m of the Indian Ocean from satellite measurements of sea surface parameters (SSTA, SSHA and SSSA as input attributes for SVM). The results, based on the common SVM application of Support Vector Regression (SVR), were validated for accuracy and reliability using the Argo STA data. Both MSE and r 2 for performance measures are improved after including SSSA for SVR (MSE decreased by 12% and r 2 increased by 11% on average). The results showed that SSSA, in addition to SSTA and SSHA, is a useful parameter that can help detect and describe the deeper ocean thermal structure, as well as improve the STA estimation accuracy. Moreover, our method can provide a useful technique for studying subsurface and deeper ocean thermal variability which has played an important role in recent global surface warming hiatus since 1998, from satellite measurements in large basin-wide scale.

Over the last 15 years, global mean surface temperatures exhibit only weak trends. Recent studies have attempted to attribute this so called temperature hiatus to several causes, amongst them incomplete sampling of the rapidly warming Arctic region. We here examine zonal mean temperature trends in satellite-based tropospheric data sets (based on data from (Advanced) Microwave Sounding Unit and Global Navigation Satellite System Radio Occultation instruments) and in global surface temperatures (HadCRUT4). Omission of successively larger polar regions from the global mean temperature calculations, in both tropospheric and surface data sets, shows that data gaps at high latitudes cannot explain the observed differences between the hiatus and the prehiatus period. Instead, the dominating causes of the global temperature hiatus are found at low latitudes. The combined use of several independent data sets, representing completely different measurement techniques and sampling characteristics, strengthens the conclusions.

The globally-averaged annual combined land and ocean surface temperature (GST) anomaly change features a slowdown in the rate of global warming in the mid-twentieth century and the beginning of the twenty-first century. Here, it is shown that the hiatus in the rate of global warming typically occurs when the internally generated cooling associated with the cool phase of the multi-decadal variability overcomes the secular warming from human-induced forcing. We provide compelling evidence that the global warming hiatus is a natural product of the interplays between a secular warming tendency due in a large part to the buildup of anthropogenic greenhouse gas concentrations, in particular CO2 concentration, and internally generated cooling by a cool phase of a quasi-60-year oscillatory variability that is closely associated with the Atlantic multi-decadal oscillation (AMO) and the Pacific decadal oscillation (PDO). We further illuminate that the AMO can be considered as a useful indicator and the PDO can be implicated as a harbinger of variations in global annual average surface temperature on multi-decadal timescales. Our results suggest that the recent observed hiatus in the rate of global warming will very likely extend for several more years due to the cooling phase of the quasi-60-year oscillatory variability superimposed on the secular warming trend.

With the extra-ordinary intensity of 170 kts, supertyphoon Haiyan devastated the Philippines in November 2013. This intensity is among the highest ever observed for tropical cyclones (TCs) globally, 35 kts well above the threshold (135kts) of the existing highest category of 5. Though there is speculation to associate global warming with such intensity, existing research indicate that we have been in a warming hiatus period, with the hiatus attributed to the La Nina-like multi-decadal phenomenon. It is thus intriguing to understand why Haiyan can occur during hiatus. It is suggested that as the western Pacific manifestation of the La Nina-like phenomenon is to pile up warm subsurface water to the west, the western North Pacific experienced evident subsurface warming and created a very favorable ocean pre-condition for Haiyan. Together with its fast traveling speed, the air-sea flux supply was 158% as compared to normal for intensification.

As a unique and high gigantic plateau, the Tibetan Plateau (TP) is sensitive and vulnerable to global climate change, and its climate change tendencies and the corresponding impact on regional ecosystems and water resources can provide an early alarm for global and mid-latitude climate changes. Growing evidence suggests that the TP has experienced more significant warming than its surrounding areas during past decades, especially at elevations higher than 4 km. Greater warming at higher elevations than at lower elevations has been reported in several major mountainous regions on earth, and this interesting phenomenon is known as elevation-dependent climate change, or elevation-dependent warming (EDW).At the beginning of the 21st century, Chinese scholars first noticed that the TP had experienced significant warming since the mid-1950s, especially in winter, and that the latest warming period in the TP occurred earlier than enhanced global warming since the 1970s. The Chinese also first reported that the warming rates increased with the elevation in the TP and its neighborhood, and the TP was one of the most sensitive areas to global climate change. Later, additional studies, using more and longer observations from meteorological stations and satellites, shed light on the detailed characteristics of EDW in terms of mean, minimum, and maximum temperatures and in different seasons. For example, it was found that the daily minimum temperature showed the most evident EDW in comparison to the mean and daily maximum temperatures, and EDW is more significant in winter than in other seasons. The mean daily minimum and maximum temperatures also maintained increasing trends in the context of EDW. Despite a global warming hiatus since the turn of the 21st century, the TP exhibited persistent warming from 2001 to 2012.Although EDW has been demonstrated by more and more observations and modeling studies, the underlying mechanisms for EDW are not entirely clear owing to sparse, discontinuous, and insufficient observations of climate change processes. Based on limited observations and model simulations, several factors and their combinations have been proposed to be responsible for EDW, including the snow-albedo feedback, cloud-radiation effects, water vapor and radiative fluxes, and aerosols forcing. At present, however, various explanations of the mechanisms for EDW are mainly derived from model-based research, lacking more solid observational evidence. Therefore, to comprehensively understand the mechanisms of EDW, a more extensive and multiple-perspective climate monitoring system is urgently needed in the areas of the TP with high elevations and complex terrains.High-elevation climate change may have resulted in a series of environmental consequences, such as vegetation changes, permafrost melting, and glacier shrinkage, in mountainous areas. In particular, the glacial retreat could alter the headwater environments on the TP and the hydrometeorological characteristics of several major rivers in Asia, threatening the water supply for the people living in the adjacent countries. Taking into account the climate-model projections that the warming trend will continue over the TP in the coming decades, this region’s climate change and the relevant environmental consequences should be of great concern to both scientists and the general public.

The recent slowdown in global warming has initiated a reanalysis of temperature data in some mountainous regions for understanding the consequences and impact that a hiatus has on the climate system. Spatiotemporal temperature variability is analyzed over the Tibetan Plateau because of its sensitivity to climate change with a station network updated to 2014, and its linkages to remote sensing–based variability of MODIS daytime and nighttime temperature are investigated. Results indicate the following: 1) Almost all stations have experienced a notable warming in the time interval 1961–2014, with most obvious warming in winter, which depends on the selected time intervals. 2) There is no clear shift from a predominant warming to a near stagnation during the most recent period (2001–present). 3) Uniform altitudinal dependence of temperature change trends could not be confirmed for all regions, time intervals, and seasons, but sometimes an altitude threshold around 3 km is apparent. 4) Most of the meteorological stations are associated with MODIS temperature warming pixels, and thus regional cooling is missing when considering only the locations of meteorological stations. In summarizing, previous studies based on station observations do not provide a complete picture for the temperature change over the Tibetan Plateau. Remote sensing–based analyses have the potential to find early signals of regional climate changes and assess the impact of global climate changes in complex regional, seasonal, and altitudinal environments.

The central United States experienced a cooling trend during the twentieth century, called the “warming hole,” most notably in the last quarter of the century when global warming accelerated. The coupled simulations of the models that participated in the Coupled Model Intercomparison Project, Phases 3 and 5 (CMIP3/5), have been unable to reproduce this abnormal cooling phenomenon satisfactorily. An unrealistic representation of the observed phasing of the Pacific Decadal Oscillation (PDO)—one of the proposed forcing mechanisms for the warming hole—in the models is considered to be one of the main causes of this effect. The CMIP5’s uncoupled Atmospheric Model Intercomparison Project (AMIP) experiment, whose duration approximately coincides with the peak warming hole cooling period, provides an opportunity, when compared with the coupled historical experiment, to examine the role of the variation in Pacific Ocean sea surface temperature (SST) in the warming hole’s formation and also to assess the skill of the models in simulating the teleconnection between Pacific SST and the continental climate in North America. Accordingly, this study compared AMIP and historical runs in the CMIP5 suite thereby isolating the role of SST forcing in the formation of the warming hole and its maintenance mechanisms. It was found that, even when SST forcing in the AMIP run was “perfectly” prescribed in the models, the skill of the models in simulating the warming hole cooling in the central United States showed little improvement over the historical run, in which SST is calculated interactively, even though the AMIP run overestimated the anti-correlation between temperature in the central United States and the PDO index. The fact that better simulation of the PDO phasing in the AMIP run did not translate into an improved summer cooling trend in the central United States suggests that the inability of the coupled CMIP5 models to reproduce the warming hole under the historical run is not mainly a result of the mismatch between simulated and observed PDO phasing, as believed.

Over the past decades, climate change in the tropical western Pacific has led to surface warming, a distinct decrease in sea surface salinity, obvious sea level rise (SLR), and ocean acidification in the South China Sea (SCS) and Coral Sea (CS), which have had profound impacts on marine ecosystems and coastal communities. The aim of this study is to examine and compare the extent of marine climate change in these two areas, and to summarize possible adaptations in response to climate change. Our results indicate that a fast rise in sea surface temperature (SST) at a rate of more than 0.07 °C decade−1 and a decrease in sea surface salinity (SSS) at a rate of more than −0.09 g kg−1 decade−1 appeared in the SCS, which are greater than that in the CS, although SST changes also show a plateau consistent with the global warming hiatus since 2000. As a proxy for marine productivity, concentrations of chlorophyll-a apparently varied with the SSS and SST changes in the two areas. Our findings suggest that marine ecosystem functions have been greatly affected by climate change through changes in tropical evaporation and rainfall. Meanwhile, persistent SLR and ocean acidification pose serious threats to low-lying coastal areas, small islands, coral-dominated reef ecosystems, and related subsistence fisheries. The sustainable development of communities in low-lying coastal zones and small islands faces significant future challenge. Adaptation strategies for mitigating the effects of climate changes need to be developed and put forward.

A study of regional temperature reconstructions of the instrumental record 1850-2016 for five global regions is presented. No evidence is found to relate warming of sea surface temperature (SST) in either hemisphere to global emissions. The rate of warming over land in the Northern Hemisphere appears to show some evidence of correlation with global emissions in five of the twelve calendar months but the statistical significance of the correlation could not be verified with station data from the region. No correlation with emissions could be found in regional temperature reconstructions for land in the Southern Hemisphere or for combined land and ocean in either hemisphere. These results taken together do not support the claim that the observed warming in surface temperatures worldwide since the Industrial Revolution is driven by fossil fuel emissions or that observed changes in tropical cyclone characteristics due to rising SST are anthropogenic.

This chapter provides an overview of the factors that will govern the rise in global mean surface temperature (GMST) over the rest of this century. We evaluate GMST using two approaches: analysis of archived output from atmospheric, oceanic general circulation models (GCMs) and calculations conducted using a computational framework developed by our group, termed the Empirical Model of Global Climate (EM-GC). Comparison of the observed rise in GMST over the past 32 years with GCM output reveals these models tend to warm too quickly, on average by about a factor of two. Most GCMs likely represent climate feedback in a manner that amplifies the radiative forcing of climate due to greenhouse gases (GHGs) too strongly. The GCM-based forecast of GMST over the rest of the century predicts neither the target (1.5 °C) nor upper limit (2.0 °C warming) of the Paris Climate Agreement will be achieved if GHGs follow the trajectories of either the Representative Concentration Pathway (RCP) 4.5 or 8.5 scenarios. Conversely, forecasts of GMST conducted in the EM-GC framework indicate that if GHGs follow the RCP 4.5 trajectory, there is a reasonably good probability (~75 %) the Paris target of 1.5 °C warming will be achieved, and an excellent probability (>95 %) global warming will remain below 2.0 °C. Uncertainty in the EM-GC forecast of GMST is primarily caused by the ability to simulate past climate for various combinations of parameters that represent climate feedback and radiative forcing due to aerosols, which provide disparate projections of future warming.

Since the mid-1990s, ocean wave reanalysis and in situ wave observations have revealed marked downward trends in wave height, exceeding −0.1 m per decade in the midlatitude North Pacific. The wave period in the tropical Pacific is also on a downward trend, exceeding −0.4 s per decade during this period. These changes in wave climate in the Pacific are attributable to recently strengthened trade winds and La Nina-like conditions in the tropical Pacific. The downward trend in significant wave height in the midlatitude North Pacific is due to strengthening of the negative phase of the Pacific-North American teleconnection. Numerical experimentations with a wave model also showed that the downward trend in the wave period in the eastern equatorial Pacific was induced not only by increased wind waves due to strengthened trade winds but also by weakened propagating swells from the midlatitude North Pacific.

Major population changes of marine mega-fauna are ongoing as global warming, and other anthropogenic drivers affect prey availability. The historical stronghold of the Eastern Rockhopper Penguin (Eudyptes chrysocome filholi) was New Zealand’s sub-Antarctic Campbell Island, but the population declined by 94 % between 1942 and 1984. The apparent mechanism of collapse was warm ocean temperatures causing an inadequate food supply. Eudyptes penguin population declines are ongoing at some breeding sites, highlighting the need to investigate the population trend on Campbell Island since 1984. We estimated the Eastern Rockhopper Penguin breeding population size through physical and photo-counts of birds and nests in 2012, and changes in colony area relative to 1984 and 1996 photographs. We estimated the 2012 population size at 33,239 breeding pairs, a 21.8 % decrease from an (adjusted) estimate of 42,528 pairs in 1984. Although substantial, the recent 1984–2012 decline occurred at a much slower rate (λ = 0.991) than the 1942–1984 decline (λ = 0.940). Despite great variation in trends between colonies ostensibly linked to differences in predation rates, the recent decline occurred primarily between 1984 and 1996, and thereafter the overall population grew. A 100-year time series of extended reconstructed sea surface temperatures (ERSST) confirmed that the population declined during warm periods and increased during cool periods, but that the initial decline began before increases in regional ERSST. Population growth after 1996 appears related to the current global warming hiatus, lower ERSST, and increased abundance of a key prey species. We predict a continuation of the long-term population decline after warming resumes.

Accounting for natural decadal variability allows better prediction of short-term trends. This study looks at the ability of individual models, which are in phase with the Interdecadal Pacific Oscillation, to simulate the current global warming slowdown. The authors highlight that the current trend could have been predicted in the 1990s with this technique and the need for consistent hindcast skills to allow reliable decadal predictions.

The role of natural decadal variability in the global warming slowdown has been hinted at, but not quantified. This study looks at decadal average surface temperature anomalies for the 1980s, 1990s and 2000s. The results show that decadal variability is a large contributor to temperature trends, but its influence has decreased, from 47% in the 1980s to 27% in the 2000s, as anthropogenic warming has increased.

National Institute of Meteorological Research, Jeju 697-845, KoreaAbstract: Despite the greenhouse gases like carbon dioxide have steadily increased in atmosphere, the overall trend of theglobal average surface air temperature has stalled during the last decade (2002-present). This phenomenon is often calledhiatus or warming pause, which is challenging the prevailing view that anthropogenic forcing causes warmingenvironment. Our study characterized the hiatus by analyzing the HadGEM2-AO (95 yrs) simulation data based onRCP8.5 scenario. The PC2 time series from the EOF of the zonal mean vertical ocean temperature has been defined asthe index that represents the warming pause. The relationship between the hiatus, ENSO and the changes in climatesystem are identified by utilizing the newly defined PC2. Since the La Nina index (defined as the negative of NINO3index) leads PC2 by about 11 months, it may be possible that the La Nina causes the warming to be interrupted. We alsoshow that the cooling of the climate system closed tied to the heat penetration into the deep ocean, indicating theweakening the warming rate is due to the oceanic heat uptake. Finally, the global warming hiatus is characterized by theanomalous warming in Arctic region as well as the intensification of the trade wind in the equatorial Pacific.Keywords: warming hiatus, HadGEM2-AO, La Nina, oceanic heat uptake요약: 대기 중 이산화탄소 등의 농도가 지속적으로 증가하고 있음에도 최근 10여 년 동안(2002-현재) 전지구 지표 온도는 거의 답보상태에 머물러 있다. 이처럼 온실기체 강제력에도 불구하고, 지구 온난화 경향이 사라진 듯 보이는 현상을 지구 온난화 멈춤(hiatus)이라 한다. 이 연구는 HadGEM2-AO가 모의한 RCP8.5 시나리오 실험(95년간) 자료를 분석하여, 온난화 멈춤 시기의 특징을 분석하였다. 온난화 멈춤 기간을 나타내는 시계열은 동서 평균한 연직 해수 온도 분포를 EOF 분석하여 구한 두 번째 PC (PC2)로 정의하였다. PC2를 이용하여 온난화 멈춤과 엔소와의 관련성, 기후시스템의 변화 등을 분석하였다. 라니냐 지수(NINO3지수에

Deep-sea warming slows down global warming Global warming seems to have paused over the past 15 years while the deep ocean takes the heat instead. The thermal capacity of the oceans far exceeds that of the atmosphere, so the oceans can store up to 90% of the heat buildup caused by increased concentrations of greenhouse gases such as carbon dioxide. Chen and Tung used observational data to trace the pathways of recent ocean heating. They conclude that the deep Atlantic and Southern Oceans, but not the Pacific, have absorbed the excess heat that would otherwise have fueled continued warming. Science , this issue p. 897