Early onset of industrial-era warming across the oceans and continents

Abstract

The evolution of industrial-era warming across the continents and oceans provides a context for future climate change and is important for determining climate sensitivity and the processes that control regional warming. Here we use post-ad 1500 palaeoclimate records to show that sustained industrial-era warming of the tropical oceans first developed during the mid-nineteenth century and was nearly synchronous with Northern Hemisphere continental warming. The early onset of sustained, significant warming in palaeoclimate records and model simulations suggests that greenhouse forcing of industrial-era warming commenced as early as the mid-nineteenth century and included an enhanced equatorial ocean response mechanism. The development of Southern Hemisphere warming is delayed in reconstructions, but this apparent delay is not reproduced in climate simulations. Our findings imply that instrumental records are too short to comprehensively assess anthropogenic climate change and that, in some regions, about 180 years of industrial-era warming has already caused surface temperatures to emerge above pre-industrial values, even when taking natural variability into account.

Characterizing and attributing the warming trend in sea and land surface temperatures

“…A similar cooling trend (about -0.14 ºC per century) is found in SL temperatures over the southern hemisphere, which is dominantly composed of oceans. These trends are consistent with the effects of ocean cooling trends that have been documented from the preindustrial times until the beginning of the 20th century, when the increase in anthropogenic forcing started to become more important (Delworth and Knutson, 2000;Stott et al, 2000;McGregor et al, 2015;Abram et al, 2016). For all sea temperature series, a moderate warming started after 1909 and, in the case of the southern hemisphere SL, the warming started after 1925 (in all cases the rate of warming is about 0.7 ºC per century).…”

Testing the consistency between changes in simulated climate and Alpine glacier length over the past millennium

“…However, they underestimate the magnitude of the changes for some (multi-)decadalscale events compared to the reconstruction of Luterbacher et al (2016). Interestingly, some models display an industrialera warming that occurred earlier or later than observed (Abram et al, 2016), with a potentially large impact on the glacier retreat over the recent period. At a regional scale for the Alps, the conclusions are similar except that the internal climate variability becomes large enough so that simulation results cover nearly the full range provided by the reconstruction, even for the decadal-scale warm or cold events.…”

Atlantic Water advection vs. glacier dynamics in northern Spitsbergen since early deglaciation

“…Abram et al, 2016;IPCC, 2014), it still remains unclear to which extent natural mechanisms may be involved. Instrumental climate data rarely cover more than the last century; sea ice observations using satellites did not even start before late 1978 (Stroeve et al, 2012).…”