The media has been reporting on the wrong NASA employee on climate. The hyper-prolific James Hansen deserves our attention, not his boss. He has yet another journal article worth reading: “Climate change and trace gases.” He explains:
In my opinion, among our papers this one probably does the best job of making clear that the Earth is getting perilously close to climate changes that could run out of our control.
Here is the lengthy abstract:
Paleoclimate data show that the Earth’s climate is remarkably sensitive to global forcings. Positive feedbacks predominate. This allows the entire planet to be whipsawed between climate states. One feedback, the “albedo flip” property of water substance, provides a powerful trigger mechanism. A climate forcing that “flips” the albedo of a sufficient portion of an ice sheet can spark a cataclysm. Ice sheet and ocean inertia provides only moderate delay to ice sheet disintegration and a burst of added global warming. Recent greenhouse gas (GHG) emissions placethe Earth perilously close to dramatic climate change that could run out of our control, with great dangers for humans and other creatures. Carbon dioxide (CO2) is the largest human-made climate forcing, but other trace constituents are important. Only intense simultaneous efforts to slow CO2 emissions and reduce non-CO2 forcings can keep climate within or near the range of the past million years. The most important of the non-CO2 forcings is methane (CH4), as it causes the 2nd largest human-made GHG climate forcing and is the principal cause of increased tropospheric ozone (O3), which is the 3rd largest GHG forcing. Nitrous oxide (N2O) should also be a focus of climate mitigation efforts. Black carbon (”black soot”) has a high global warming potential (~2000, 500, and 200 for 20, 100 and 500 years, respectively) and deserves greater attention. Some forcings are especially effective at high latitudes, so concerted efforts to reduce their emissions could still “save the Arctic”, while also having major benefits for human health, agricultural productivity, and the global environment.
