Hegerl's research[9][10][11] in the natural variability of climate and changes in climate due to natural and anthropogenic changes in radiative forcing (such as greenhouse warming, climate effects of volcanic eruptions and changes in solar radiation). Hegerl has also led well-known research on the attribution of modern climate change to anthropogenicgreenhouse gas emission.
She led a 2006 study examiningclimate sensitivity, then commonly accepted as 1.5 to 4.5K in response to a doubling of atmospheric CO2, to review observational studies suggesting that climate sensitivity could be as much as 7.7K or even exceed 9K. By using large-ensemble energy balance modelling to simulate temperature responses to historic changes in theradiative forcing effect of solar changes, volcanic eruptions and greenhouse gases, and comparing this toclimate reconstructions, they produced an independent estimate that climate sensitivity was probably within the range of 1.5 to 6.2K.[10] In an interview withThe Washington Times, Hegerl said "Our reconstruction supports a lot of variability in the past".[12]
She is a co-ordinating lead author on theIPCC Fourth Assessment Report for Working Group I in the chapter on "Understanding and Attributing Climate Change".[13] Her 2006 reconstruction was cited in the chapter on "Paleoclimate" in support of the conclusion that the 20th century was likely to have been the warmest in the Northern Hemisphere for at least 1,300 years.[14]
She was a member of a team which reviewed recent reconstructions of thetemperature record of the past 1000 years, and in 2007 published their own reconstruction from proxies, finding that the maximum pre-industrial temperature in 1,000 years had been significantly exceeded by recent instrumental temperatures.[11]
"Annular Modes in the Extratropical Circulation. Part II: Trends",[16]
"Simulation of the influence of solar radiation variations on the global climate with an ocean-atmosphere general circulation", by U Cubasch, R Voss, GC Hegerl, J Waszkewitz, T. J. Crowley – Climate Dynamics, 1997
"Multi-fingerprint detection and attribution analysis of greenhouse gas, greenhouse gas-plus-aerosol and solar forced climate change", by G. C. Hegerl, K. Hasselmann, U. Cubasch, J. F. B. Mitchell, E. Roeckner, R. Voss and J. Waszkewitz
"Detecting Greenhouse-Gas-Induced Climate Change with an Optimal Fingerprint Method",[17]
"Detection of climate change and attribution of causes", by JFB Mitchell, DJ Karoly, GC Hegerl, FW Zwiers, MR … – Climate Change 2001: The Scientific Basis, 2001
"The Effect of Local Sea Surface Temperatures on Atmospheric Circulation over the Tropical Atlantic"[18]
"On multi-fingerprint detection and attribution of greenhouse gas- and aerosol forced climate change"[19]
In 2016, Professor Hegerl won theHans Sigrist Prize "for her groundbreaking scientific work in this year’s prize field, 'The Human Fingerprint on the Earth System'"[23] In 2018 she was made an honoraryDoctor of Science by Leeds University.[24]
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