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The monthly global and regional variability in Earth's radiation balance is examined using correlations and regressions between atmospheric temperatures and water vapor with top‐of‐atmosphere outgoing longwave (OLR), absorbed shortwave (ASR), and net radiation ( R T = ASR − OLR). Anomalous global mean monthly variability in the net radiation is surprisingly large, often more than ±1 W m −2 , and arises mainly from clouds and transient weather systems. Relationships are strongest and positive between OLR and temperatures, especially over land for tropospheric temperatures, except in the deep tropics where high sea surface temperatures are associated with deep convection, high cold cloud tops and thus less OLR but also less ASR. Tropospheric vertically averaged temperatures (surface = 150 hPa) are thus negatively correlated globally with net radiation (−0.57), implying 2.18 ± 0.10 W m −2 extra net radiation to space for 1°C increase in temperature. Water vapor is positively correlated with tropospheric temperatures and thus also negatively correlated with net radiation; however, when the temperature dependency of water vapor is statistically removed, a significant positive feedback between water vapor and net radiation is revealed globally with 0.87 W m −2 less OLR to space per millimeter of total column water vapor. The regression coefficient between global R T and tropospheric temperature becomes −2.98 W m −2 K −1 if water vapor effects are removed, slightly less than expected from blackbody radiation (−3.2 W m −2 K −1 ), suggesting a positive feedback from clouds and other processes. Robust regional structures provide additional physical insights. The observational record is too short, weather noise too great, and forcing too small to make reliable estimates of climate sensitivity.
Earth’s energy imbalance is associated with the forcings of the climate system and how it responds, including all of the feedbacks. EEI is actually the net outcome, but climate models facilitate the understanding of the actual flows of energy through the climate system and in turn are a key step toward estimating the consequences. Hence, climate models are extensively used to encapsulate the knowledge and understanding of the climate system and how it works, and for making projections of the future. However, as noted in Chapter 1, the models are not perfect and involve approximations and assumptions. The IPCC approach has been very democratic in that all models have been treated equally even though some models have been shown to contain substantial errors. It makes sense to use only the models that perform well. Of course, all models contain errors, but some models actually violate physical principles, such as conservation of mass or energy, and these should not be used. Certainly, some models are a lot better than others.
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The atmosphere is the layer of air surrounding Earth. The atmosphere consists of four layers: the troposphere, stratosphere, mesosphere, and thermosphere. Figure 6.1 shows the different layers and how the temperature changes with height from the ground to the very thin top of the atmosphere. The troposphere, the lowest layer of the atmosphere, is where we live and where weather occurs. Temperatures generally decrease with height. The boundary between the troposphere and the stratosphere is called the tropopause, which is higher in the tropics and lower at mid to high latitudes. The temperature in the stratosphere generally increases with height because it encompasses the ozone layer which absorbs ultraviolet (UV) rays from the Sun. In the mesosphere the temperature again decreases with height and it is well mixed with a similar composition to the troposphere, except there is little water vapor. The thermosphere is the uppermost layer of the atmosphere where the temperature increases with height because it is directly heated by the Sun. Above about the mesopause, which divides the mesosphere from the thermosphere, the molecules of the atmosphere become ionized by the active very shortwave radiation from the Sun (X-rays, UV) or cosmic rays (which may come from elsewhere) that do not make it to the lower levels, and their abundance is greatly affected by solar activity. The ionosphere, which overlaps with the other layers defined by temperature, plays a major role in transmission of radio waves over great distances around the world. At these very high levels of the atmosphere, above about 80 km altitude, the composition of the atmosphere is very different than at lower levels.
Global mean surface temperatures ( GMST ) exhibited a smaller rate of warming during 1998–2013, compared to the warming in the latter half of the 20th Century. Although, not a “true” hiatus in the strict definition of the word, this has been termed the “global warming hiatus” by IPCC (2013). There have been other periods that have also been defined as the “hiatus” depending on the analysis. There are a number of uncertainties and knowledge gaps regarding the “hiatus.” This report reviews these issues and also posits insights from a collective set of diverse information that helps us understand what we do and do not know. One salient insight is that the GMST phenomenon is a surface characteristic that does not represent a slowdown in warming of the climate system but rather is an energy redistribution within the oceans. Improved understanding of the ocean distribution and redistribution of heat will help better monitor Earth's energy budget and its consequences. A review of recent scientific publications on the “hiatus” shows the difficulty and complexities in pinpointing the oceanic sink of the “missing heat” from the atmosphere and the upper layer of the oceans, which defines the “hiatus.” Advances in “hiatus” research and outlooks (recommendations) are given in this report.
Climate change from increased greenhouse gases arises from a global energy imbalance at the top of the atmosphere (TOA). TOA measurements of radiation from space can track changes over time but lack absolute accuracy. An inventory of energy storage changes shows that over 90% of the imbalance is manifested as a rise in ocean heat content (OHC). Data from the Ocean Reanalysis System, version 4 (ORAS4), and other OHC-estimated rates of change are used to compare with model-based estimates of TOA energy imbalance [from the Community Climate System Model, version 4 (CCSM4)] and with TOA satellite measurements for the year 2000 onward. Most ocean-only OHC analyses extend to only 700-m depth, have large discrepancies among the rates of change of OHC, and do not resolve interannual variability adequately to capture ENSO and volcanic eruption effects, all aspects that are improved with assimilation of multivariate data. ORAS4 rates of change of OHC quantitatively agree with the radiative forcing estimates of impacts of the three major volcanic eruptions since 1960 (Mt. Agung, 1963; El Chichón, 1982; and Mt. Pinatubo, 1991). The natural variability of the energy imbalance is substantial from month to month, associated with cloud and weather variations, and interannually mainly associated with ENSO, while the sun affects 15% of the climate change signal on decadal time scales. All estimates (OHC and TOA) show that over the past decade the energy imbalance ranges between about 0.5 and 1 W m−2. By using the full-depth ocean, there is a better overall accounting for energy, but discrepancies remain at interannual time scales between OHC- and TOA-based estimates, notably in 2008/09.
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Changes in ocean heat content (OHC), salinity, and stratification provide critical indicators for changes in Earth's energy and water cycles. These cycles have been profoundly altered due to the emission of greenhouse gasses and other anthropogenic substances by human activities, driving pervasive changes in Earth's climate system. In 2022, the world's oceans, as given by OHC, were again the hottest in the historical record and exceeded the previous 2021 record maximum. According to IAP/CAS data, the 0-2000 m OHC in 2022 exceeded that of 2021 by 10.9 ± 8.3 ZJ (1 Zetta Joules = 1021 Joules); and according to NCEI/NOAA data, by 9.1 ± 8.7 ZJ. Among seven regions, four basins (the North Pacific, North Atlantic, the Mediterranean Sea, and southern oceans) recorded their highest OHC since the 1950s. The salinity-contrast index, a quantification of the "salty gets saltier-fresh gets fresher" pattern, also reached its highest level on record in 2022, implying continued amplification of the global hydrological cycle. Regional OHC and salinity changes in 2022 were dominated by a strong La Niña event. Global upper-ocean stratification continued its increasing trend and was among the top seven in 2022.由于人类活动排放温室气体, 全球能量和水循环已经发生了显著的变化, 驱动了气候系统的一系列变异. 海洋热含量、 盐度和层结变化是地球系统能量和水循环的重要指针. 2022 年, 全球海洋上层 2000 米热含量再破记录, 海洋成为有现代记录以来最热的一年. 据中国科学院大气物理研究所的测算, 2022 年 0–2000 米海洋热含量超过 2021 年 10.9 ± 8.3 泽塔焦耳 (1 泽塔焦耳= 1021焦耳). 与之一致, 美国国家海洋和大气管理局国家环境信息中心的测算为 9.1 ± 8.7 泽塔焦耳. 在所研究的 7 个海盆中, 北太平洋、 北大西洋、 地中海、 南大洋这 4 个海盆的 2022 年度热含量均创下了自上世纪 50 年代以来的新记录. 此外, 定量化测算海洋盐度 “咸变咸, 淡变淡” 变化趋势的 “盐度差指数” 也在 2022 年达到过去半世纪以来的最高值, 反映了全球水循环在不断加速. 在区域尺度, 海洋热含量和盐度变化显示出较强的拉尼娜事件的影响. 最后, 全球上层 2000 米海洋层结也持续加强, 2022 年全球海洋层结处于有现代记录以来的第 7 高位.
No abstract is provided for this article.
The heat budget has been computed locally over the entire globe for each month of 1988 using compatible top-of-the-atmosphere radiation from the Earth Radi
New estimates of the poleward energy transport based on atmospheric reanalyses from the National Centers for Environmental Prediction–National Center for Atmospheric Research (NCEP–NCAR) and the European Centre for Medium-Range Weather Forecasts are presented. The analysis focuses on the period from February 1985 to April 1989 when there are reliable top-of-the-atmosphere radiation data from the Earth Radiation Budget Experiment. Annual mean poleward transports of atmospheric energy peak at 5.0 ± 0.14 PW at 43°N and with similar values near 40°S, which is much larger than previous estimates. The standard deviation of annual and zonal mean variability from 1979 to 1998 is mostly less than 0.15 PW (1%–3%). Results are evaluated by computing the implied ocean heat transports, utilizing physical constraints, and comparing them with direct oceanographic estimates and those from successful stable coupled climate models that have been run without artificial flux adjustments for several centuries. Reasonable agreement among ocean transports is obtained with the disparate methods when the results from NCEP–NCAR reanalyses based upon residually derived (not model-generated) methods are used, and this suggests that improvements have occurred and convergence is to the true values. Atmospheric transports adjusted for spurious subterranean transports over land areas are inferred and show that poleward ocean heat transports are dominant only between 0° and 17°N. At 35° latitude, at which the peak total poleward transport in each hemisphere occurs, the atmospheric transport accounts for 78% of the total in the Northern Hemisphere and 92% in the Southern Hemisphere. In general, a much greater portion of the required poleward transport is contributed by the atmosphere than the ocean, as compared with previous estimates.
A detailed analysis of hourly precipitation from 60°N to 60°S for the covariability is performed at 0.25° resolution using the new CMORPH dataset. For all points, correlations are computed with surrounding points both concurrently and for various leads and lags up to a day. Results are more coherent over the oceans than land; the contours of constant correlation tend to be elliptical, oriented northeast–southwest in the northern extratropics and southeast–northwest in the southern extratropics. An ellipse is fitted to the correlation pattern, and major and minor axis vectors and eccentricity are mapped. Based upon both the isotropic correlations and ellipse, points are allocated to one of 20 clusters, and 16 are documented. Over the main extratropical ocean storm tracks, correlations exceed 0.8 for points 50 km distant and fall to about 0.3 at about 5° radius. In the tropics values drop to 0.65 within 50 km and 0.2 at 5° radius. Over land, values are lower in summer and drop to 0.1 at 5° radius. Decorrelation e-folding distances range from less than 50 km over land to 200 km over extratropical ocean storm tracks. The movement of precipitation is compared with mean atmospheric winds. The lead–lag relationships indicate movement of systems but reveal the relatively short lifetimes of precipitation, of less than 12 h, even taking movement into account. The orientation of the ellipse reflects the structures of rain phenomena (fronts, etc.) rather than movement. These statistics demonstrate that daily averages fail to capture the essential character of precipitation.
The increased concentration of greenhouse gases in the atmosphere from human activities traps heat within the climate system and increases ocean heat content (OHC). Here, we provide the first analysis of recent OHC changes through 2021 from two international groups. The world ocean, in 2021, was the hottest ever recorded by humans, and the 2021 annual OHC value is even higher than last year's record value by 14 ± 11 ZJ (1 zetta J = 1021 J) using the IAP/CAS dataset and by 16 ± 10 ZJ using NCEI/NOAA dataset. The long-term ocean warming is larger in the Atlantic and Southern Oceans than in other regions and is mainly attributed, via climate model simulations, to an increase in anthropogenic greenhouse gas concentrations. The year-to-year variation of OHC is primarily tied to the El Niño-Southern Oscillation (ENSO). In the seven maritime domains of the Indian, Tropical Atlantic, North Atlantic, Northwest Pacific, North Pacific, Southern oceans, and the Mediterranean Sea, robust warming is observed but with distinct inter-annual to decadal variability. Four out of seven domains showed record-high heat content in 2021. The anomalous global and regional ocean warming established in this study should be incorporated into climate risk assessments, adaptation, and mitigation.人类活动导致大气中温室气体的浓度上升,造成了地球系统的净热量吸收和海洋热含量增加。本文发布了两个国际机构的2021年海洋热含量数据,数据表明:2021年海洋升温持续——成为有现代海洋观测记录以来海洋最暖的一年。相对于2020年,2021年全球海洋上层2000米热含量上升了14 ± 11 ZJ (1 zetta J = 1021 J)(IAP/CAS数据)、以及16 ± 10 ZJ(NOAA/NCEI数据)。海洋长期变暖趋势在南大洋、中低纬度大西洋区域更强,地球系统模式的单个因子强迫实验证明,温室气体增加是主要的驱动因子;而年际尺度的海洋热含量变化主要受到厄尔尼诺-南方涛动模态调控。此外,本文给出了全球7个主要海域的海洋变暖测算,发现地中海、北大西洋、南大洋、北太平洋海区温度均创历史新高。最后,本文提出需要充分将全球和区域海洋变暖的影响纳入气候风险评估、气候变化影响和应对当中。.
