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Jim Hansen

b. 1941

Jim Hansen, b. 1941, atmospheric physicist and climatologist

Jim Hansen, b. 1941, NASA GISS director, atmospheric physicist, author and environment activist.

  • Nationality
  • American

  • Subject
  • Environment

  • Fields
  • Climatology, atmospheric physics, astronomy

  • Distinctions
  • Carl-Gustaf Rossby Research Medal

    Member of the National Academy of Sciences

    Klopsteg Memorial Award, 2011

  • Posts
  • NASA GISS (Goddard Institute for Space Studies) atmospheric physicist and director, 1981 - 2013.

    Adjunct professor in the Department of Earth and Environmental Sciences, Columbia University.

    Head of the Program on Climate Science, Awareness and Solutions at Columbia University's Earth Institute, 2014.

  • Publications
  • Global warming in the twenty-first century: an alternative scenario, 2000, paper.

    Can We Defuse the Global Warming Time Bomb?, 2003, paper.

    "Storms of My Grandchildren" is his first book, published in 2009.

    His 2012 TED Talk is entitled: Why I must speak out about climate change.

    In a famous 2007 paper, Dr. Hansen demonstrated through paleoclimate data that the ice sheets of the polar regions may not support the IPCC prediction of a 59 cm rise in sea level by the end of the 21st century.

    Global Surface Temperature Change, 2010, a paper describing the latest analysis of global temperature fluctuations.

  • Theories
  • Other greenhouse gases, apart from $CO_2$, which contribute considerably to global warming.

    Aerosols off-setting fossil fuel burning.

    "Fast-feedback" mechanism would lead to ice sheet disintegration.

    Contested the IPCC prediction of a 59 cm rise in sea level by the end of the 21st century, proposing a much higher rise may be possible due to the 'flip' scenario.

    Correlations of ice-melting and prediction scenarios.

    Hansen's early work in space science at the Goddard Institute for Space Studies, and other institutes, included radiative transfer models. These models analysed the Venusian atmosphere, which has been described as a 'run-away climate change' state. He later adapted these models to study Earth's atmosphere, in particular the effect of aerosols and trace gases on climate.

    Black Carbon (from incomplete burning) and other aerosols have an effect on surface temperatures.

  • Experiments/Discoveries
  • Satellite remote sensing of Earth's atmosphere and surface, the interpretation of data, and long-term global change.

    Global Circulation Models

    Observations of Venus, and the composition and history of its atmosphere.

    Venusian clouds ice particles upper size limit, as predicted by Hansen's radiative transfer model, confirmed by probe observation readings, and that clouds are composed of sulphur dioxide and sulfuric acid.

    Ground-based meteorological stations data used to determine the warming of the planet at 0.5-0.7°C between 1880 and 1985, and 0.8°C by 2006. Hansen countered the argument that the warming was due to the urban heat island effect, causing a bias in the way the data was measured and interpreted, demonstrating that the warming was anthropogenic in origin.

Jim Hansen, b. 1941, NASA GISS atmospheric physicist, author and environment activist.

Environmentalist Hansen
Jim Hansen speaking at a congressional hearing on climate change in 1988

A true environment hero, Dr. Hansen has been an outspoken proponent of action against climate change causes for 40 years. His 2000 paper "Global warming in the twenty-first century: an alternative scenario" presented many aspects of the debate which were not on the popular agenda, in particular drawing attention to the other greenhouse gases, apart from CO2, which contributed considerably to global warming, and the issue of aerosols off-setting fossil fuel burning.

Dr. Hansen predicted that a "fast-feedback" mechanism would lead to ice sheet disintegration: since proven to be correct. This mechanism raises the fear that ice melting would lead to a non-regular sea-level rise, and far beyond that predicted by the cautious IPCC reports.

Dr. Hansen has been very outspoken about the degree of alarm people should feel about climate change, and the gap between this danger and the political and economic responses. In 2008 interviews on TV and the printed press, Dr. Hansen proposed equating the actions of people, such as fossil fuel CEOs, in their deliberate promulgation of false information, to any other crimes against humanity.

Fast-Feedback acceleration of ice melt

Icemelt
Pine Island Glacier calving, Antarctica, 2013

In a famous 2007 paper, Dr. Hansen demonstrated through paleoclimate data that the ice sheets of the polar regions may not support the IPCC prediction of a 59 cm rise in sea level by the end of the 21st century.

Geological studies suggest that ice does not melt in a linear fashion, but is more likely to change state in sudden 'flips'. One shocking possibility is that sea levels may rise by far more than predicted. When temperatures rise by 3°C, there is geological evidence to fear a 25m or more rise in sea levels. This is not an unknown occurrence for the planet - it happened as recently as 3.5 million years BP (Before Present).

Icemelt
Icemelt between 1989 and 2011, Bear Glacier, Alaska

Dr. Hansen takes pains to emphasise that the report is not meant to be alarmist, and acknowledges that there are many parameters involving broad ranges of uncertainty. One of these is the ice sheet response time. However, since the 2007 report, large parts of the ice shelf have in fact broken off far earlier than expected, giving credence to the propositions.

Dr. Hansen wrote in his 2003 paper Can We Defuse the Global Warming Time Bomb?: "halting global warming requires urgent, unprecedented international cooperation, but the needed actions are feasible and have additional benefits for human health, agriculture and the environment."






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