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Filed under: — stefan @ 18 July 2018

Established understanding of the AMOC (sometimes popularly called Gulf Stream System) says that a weaker AMOC leads to a slightly cooler global mean surface temperature due to changes in ocean 必威官网heat storage.但是现在,anew paperinNature相反的说法,甚至预言了全球变暖的快速阶段。What's the story?

By Stefan Rahmstorf and Michael Mann

In 1751,the captain of an English slave-trading ship made a historic discovery.While sailing at latitude 25°N in the subtropical North Atlantic Ocean,亨利·埃利斯上尉把一个“桶形海规”从温暖的水面下降到深海。By means of a long rope and a system of valves,water from various depths could be brought up to the deck,where its temperature was read from a built-in thermometer.令他吃惊的是,埃利斯船长发现深水冰冷。

These were the first ever recorded temperature measurements of the deep ocean.And they revealed what is now known to be a fundamental feature of all the world oceans: deep water is always cold.The warm waters of the tropics and subtropics are confined to a thin layer at the surface;the 必威官网heat of the sun does not slowly warm up the depths as might be expected.Ellis wrote:

“这个实验,which seem'd at first but mere food for curiosity,在过渡时期对我们非常有用。By its means we supplied our cold bath,and cooled our wines or water at pleasure;which is vastly agreeable to us in this burning climate."

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El Niño and the record years 1998 and 2016

Filed under: — stefan @ 4 November 2017

2017 is set to be one of warmest years on record.Gavin has been making regular forecasts of where 2017 will end up,and it is now set to be #2 or #3 in the list of hottest years:

In either case it will be the warmest year on record that was not boosted by El Niño.I've been asked several times whether that is surprising.After all,厄尔尼诺事件,which pushed up the 2016 temperature,就在我们后面。El Niño conditions prevailed in the tropical Pacific from October 2014 throughout 2015 and in the first half of 2016,giving way to a cold2016年下半年拉尼奥活动.(Note that global temperaturelags El Niño variations by several monthsso this La Niña should have cooled 2017.)More »

O Say Can You CO2…

Filed under: — group @ 12 October 2017


TheOrbiting Carbon Observatory(OCO-2) was launched in 2014 to make fine-scale measurements of the total column concentration of CO2in the atmosphere.As luck would have it,the initial couple of years of data from OCO-2 documented a period with the fastest rate of CO2 increase ever measured,more than 3 ppm per year(Jacobson et al,2016;Wang et al,2017)during a huge El Niño event that also saw global temperatures spike to record levels.

作为本周出版的一系列OCO-2论文的一部分,a newSciencepaper byJunjie Liu and colleaguesused NASA's comprehensive Carbon Monitoring System to analyze millions of measurements from OCO-2 and other satellites to map the impact of the 2015-16 El Niño on sources and sinks of CO2,深入了解控制碳气候反馈的机制。

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  1. J.Wang,N.Zeng,MWang,f.Jiang,H.Wang,and Z.Jiang,"Contrasting terrestrial carbon cycle responses to the two strongest El Niño events: 1997–98 and 2015–16 El Niños",Earth System Dynamics Discussions,pp.1-32,2017.
  2. J.Liu,K.W.Bowman,D.S.Schimel,N.C.Parazoo,Z.Jiang,MLee,A.A.Bloom,D.Wunch,C.Frankenberg,Y.Sun,C.W.O'Dell,K.R.格尼D.Menemenlis,MGierach,D.酥脆的,and A.洗脱,"Contrasting carbon cycle responses of the tropical continents to the 2015–2016 El Niño",Science,vol.358,pp.EAAM5690,2017.

Predicting annual temperatures a year ahead

Filed under: -加文,2016年9月16日

I have a post atNate Silver's 538 siteon how we can predict annual surface temperature anomalies based on El Niño and persistence – including a (by now unsurprising) prediction for a new record in 2016 and a slightly cooler,but still very warm,2017.

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Australian silliness and July temperature records

Filed under: — gavin @ 16 August 2016

Some of you that followmy twitter accountwill have already seen this,but there was a particularly amusing episode of Q&A on Australian TV that pitted Prof.Brian Cox against a newly-elected politician who is known for his somewhat fringe climate ‘contrarian' views.The resulting exchanges were fun:
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Comparing models to the satellite datasets

How should one make graphics that appropriately compare models and observations?There are basically two key points (explored inmore depth here)–比较应“像”或“像”,不同的不确定性来源应该是清楚的,whether uncertainties are related to ‘weather' and/or structural uncertainty in either the observations or the models.There are unfortunately many graphics going around that fail to do this properly,and some prominent ones are associated with satellite temperatures made by John Christy.This post explains exactly why these graphs are misleading and how more honest presentations of the comparison allow for more informed discussions of why and how these records are changing and differ from models.
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Filed under: — gavin @ 21 January 2016

没人惊讶,2015 was clearly a record year in all the surface temperature analyses (GISTEMP,NOAA,HadCRUT4,Cowtan&Way,JMA+伯克利地球).There is a lot of discussion of this in the press,and on therelevant websites,so not much to add here.有几个数字没有进入官方声明(audio) though…

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Thoughts on 2014 and ongoing temperature trends

Filed under: — gavin @ 22 January 2015

Last Friday,NASA GISS andNOAA NCDChad apress conferenceand jointly announced theend-of-year analysis对于2014年全球地表温度异常,in both analyses,came out top.和你一样may have noticed,this got much more press attention than their joint announcement in 2013 (which wasn't a record year).

In press briefings and interviews I contributed to,I mostly focused on two issues – that 2014 was indeed the warmest year in those records (though by a small amount),and the continuing long-term trends in temperature which,since they are predominantly driven by increases in greenhouse gases,are going to continue and hence produce (on a fairly regular basis) continuing record years.对这些问题的回应主要是直截了当的,which is good (if sometimes a littlesurprising),但也提出了一些有趣的问题…
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It never rains but it pause

Filed under: — gavin @ 4 March 2014

There has been averitable delugeof new papers this month related to recent trends in surface temperature.There are analyses of the CMIP5 ensemble,new model runs,analyses of complementary observational data,试图和解,一直到评论如何在媒体和Twitter上涵盖这个话题。We will attempt to bring the highlights together here.作为背景,it is worth reading ourpreviousdiscussions,和碎片一起学家西蒙·多纳andTaminoto help put in context what is being discussed here.

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Going with the wind

Filed under: — group @ 17 February 2014

A new paper in Nature Climate Change out this week by英国和其他国家与其他一些最近的论文一起寻求了解导致所谓的全球变暖“减速”的气候动力学。As we and others have pointed out previously (e.g.在这里),全球平均气温可能会偏离长期趋势10年或更长时间,这一事实并不令人惊讶。Moreover,it's not even clear that the deviation has been as large as is commonly assumed (as discussed e.g.在Cowtan and Way studyearlier this year),and has统计意义不大in any case.Nevertheless,it's still interesting,and there is much to be learned betway体育手机版about the climate system from studying the details.

Several studies have shown that much of the excess 必威官网heating of the planet due to the radiative imbalance from ever-increasing greenhouses gases has gone into the ocean,rather than the atmosphere (see e.g.Foster and RahmstorfandBalmaseda et al.).In their new paper,England et al.这表明海洋热吸收的增加——主要发生在热带太平洋——与贸易风的异必威官网常增强有关。Stronger trade winds push warm surface water towards the west,and bring cold deeper waters to the surface to replace them.这会升高温跃层(暖地表水和冷深层水之间的边界)。and increases the amount of 必威官网heat stored in the upper few hundred meters of the ocean.Indeed,this is what happens every time there is a major La Niña event,which is why it is globally cooler during La Niña years.One could think of the last ~15 years or so as a long term "La-Niña-like" anomaly (punctuated,当然,by actual El Niño (like the exceptionally warm years 1998,2005) and La Niña events (like the relatively cool 2011).

A very consistent understanding is thus emerging of the coupled ocean and atmosphere dynamics that have caused the recent decadal-scale departure from the longer-term global warming trend.That understanding suggests that the "slowdown" in warming is unlikely to continue,as England explains in his guest post,下面。–Eric Steig

Guest commentary by Matthew England (UNSW)

For a long time now climatologists have been tracking the global average air temperature as a measure of planetary climate variability and trends,even though this metric reflects just a tiny fraction of Earth's net energy or 必威官网heat content. But it's used widely because it's the metric that enjoys the densest array of in situ observations. The problem of course is that this quantity has so manybumps and kinks,暂停和加速that predicting its year-to-year path is a big challenge.上个世纪,no single forcing agent isclearer比人为温室气体,yet zooming into years or decades,变化模式成为信号,not the noise. Yet despite these basics of climate physics,any slowdown in the overall temperature trend sees lobby groups falsely claim that global warming is over.Never mind that the globe – our planet – spans the oceans,atmosphere,land and ice systems in their entirety.

This was one of the motivations for our study out this week inNature Climate Change (England等人,2014)With the global-average surface air temperature (SAT) more-or-less steady since 2001,scientists have been seeking to explain the climate mechanics of the slowdown in warming seen in the observations during 2001-2013.One simple way to address this is to examine what is different betway体育手机版about the recent decade compared to the preceding decade when the global-mean SAT metric accelerated.This can be quantified via decade-mean differences,or via multi-decadal trends,which are roughly equivalent if the trends are more-or-less linear,or if the focus is on the low frequency changes.

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  1. G.Foster,and S.Rahmstorf,"Global temperature evolution 1979–2010",Environmental Research Letters,vol.6,pp.044022,2011。
  2. M.A.Balmaseda,K.E.Trenberth,E.Källén,"Distinctive climate signals in reanalysis of global ocean 必威官网heat content",Geophysical Research Letters,vol.40,pp.1754-1759,2013.
  3. M.H.England,S.McGregor,P.Spence,G.A.Meehl,A.Timmermann,W.Cai,A.S.Gupta,M.J.McPhaden,A.Purichand A.Santoso"Recent intensification of wind-driven circulation in the Pacific and the ongoing warming hiatus",Nature Climate Change,vol.4,pp.222-227,2014.