[MCN] RealClimate update: How good have climate models been at truly predicting the future? "remarkably well. "

[Lance Olsen]

How good have climate models been at truly predicting the future?
Filed under: Climate modelling <http://www.realclimate.org/index.php/archives/category/climate-science/climate-modelling/> Climate Science <http://www.realclimate.org/index.php/archives/category/climate-science/> Greenhouse gases <http://www.realclimate.org/index.php/archives/category/climate-science/greenhouse-gases/> Instrumental Record <http://www.realclimate.org/index.php/archives/category/climate-science/instrumental-record/> statistics <http://www.realclimate.org/index.php/archives/category/statistics/> — gavin @ 4 December 2019

http://www.realclimate.org/index.php/archives/2019/12/how-good-have-climate-models-been-at-truly-predicting-the-future/ <http://www.realclimate.org/index.php/archives/2019/12/how-good-have-climate-models-been-at-truly-predicting-the-future/>
Opening pargraphs

A new paper from Hausfather and colleagues has just been published with the most comprehensive assessment of climate model projections since the 1970s. Bottom line? Once you correct for small errors in the projected forcings, they did remarkably well.

Climate models are a core part of our understanding of our future climate. They also have been frequently attacked by those dismissive of climate change, who argue that since climate models are inevitably approximations they have no predictive power, or indeed, that they aren’t even scientific <http://www.realclimate.org/index.php/archives/2005/01/is-climate-modelling-science/>.

In an upcoming paper <http://www.realclimate.org/index.php/archives/2019/12/how-good-have-climate-models-been-at-truly-predicting-the-future/#ITEM-22891-0> in Geophysical Research Letters, Zeke Hausfather, Henri Drake, Tristan Abbott and I took a look at how well climate models have actually been able to accurately project warming in the years after they were published. This is an extension of the comparisons we have been making on RealClimate <http://www.realclimate.org/index.php/climate-model-projections-compared-to-observations/> for many years, but with a broader scope and a deeper analysis. We gathered all the climate models published between 1970 and the mid-2000s that gave projections of both future warming and future concentrations of CO2 and other climate forcings – from Manabe (1970) and Mitchell (1970) through to CMIP3 in IPCC 2007.

We found that climate models – even those published back in the 1970s – did remarkably well, with 14 out of the 17 projections statistically indistinguishable from what actually occurred.



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2016  - “Climate change impacts have now been documented across every ecosystem on Earth, despite an average warming of only ~1°C so far.”

Scheffers et al. The broad footprint of climate change from genes to biomes to people. Science, 11 NOVEMBER 2016

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2011 - "  …  analysis suggests that despite high-level statements to the contrary, there is now little to no chance of maintaining the global mean surface temperature at or below 2C. Moreover, the impacts associated with 2C have been revised upwards, sufficiently so that 2C now more appropriately represents the threshold between ‘dangerous’ and ‘extremely dangerous’ climate change."
 
Kevin Anderson and Alice Bows. Beyond ‘dangerous’ climate change: emission scenarios for a new world.Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences (2011)

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2006 - “Climate change is not a new topic in biology...... Observations of range shifts in parallel with climate change ... date back to the mid-1700s.”

“This review  …  deals exclusively with observed responses of wild biological species and systems ….  “

"A surprising result is the high proportion of species responding to recent, relatively mild climate change (global average warming of 0.6 C)." 

Parmesan, Camille. Ecological and Evolutionary Responses to Recent Climate Change. The Annual Review of Ecology, Evolution, and Systematics  37: pp. 637-69. 2006.

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2004 --"Between 1C and 2C increases in global mean temperatures most species, ecosystems and landscapes will be impacted and adaptive capacity will become limited. With the already ongoing high rate of climate change, the decline in biodiversity will therefore accelerate and simultaneously many ecosystem services will become less abundant."

Rik Leemans and Bas Eickhout. Another reason for concern: regional and global impacts on ecosystems for different levels of climate change. Global Environmental Change 14 (2004) 219–228

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2002 - “Although we are only at an early stage in the projected trends of global warming, ecological responses to recent climate change are already clearly visible.”

Walther et al, “Ecological responses to recent climate change.” Nature, March 28, 2002



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