clair031

Summary .   The U. S. government released its Third National Climate Assessment in May, 2014.   It shows that emissions from human use of fossil fuels since the industrial revolution began are reflected in increased carbon dioxide concentrations in the atmosphere, and that this is directly responsible for the increase in the long-term global average temperature.   This post summarizes these findings, affirming their validity beyond any credible scientific doubt. A future post will consider the Assessment’s climate findings.   Warming has already had adverse effects across the U. S. , including heat, drought, wildfires, changes in availability of water, floods, ocean storm surges, extreme weather and climate events and socioeconomic effects.   Worsening of these trends is foreseen during this century. Introduction .   The Third National Climate Assessment (NCA ) was issued May 6, 2014 as mandated under the Global Change Research Act of 1990 to “assist ...

Summary .   Among the documented effects of global warming has been a rise of the average sea level around the globe since 1900.   This post explains, in tutorial fashion, how this happens. First, the water in the oceans expands in volume as its temperature increases.   Expansion is constrained to occur only in the upward direction, leading to sea level rise.   Second, land-based glaciers and ice sheets melt from their upper surfaces as the air they contact warms above the melting point of water.   Third, ice shelves buoyed by the ocean in Antarctica melt from their lower surfaces as the ocean circulating under them warms.   All these processes contribute to observed sea level rise.   Both melting processes are expected to continue indefinitely as long as warming produces temperatures in the air and in the underlying ocean that remain above the melting point.   Introduction .   One of the consequences of global warming identified by clima...

Summary .   The Intergovernmental Panel on Climate Change issued Part 3 of its Fifth Assessment Report, “Climate Change 2014: Mitigation of Climate Change ”, on April 13, 2014 .   Part 3 reviews recent historical results on the increase in atmospheric greenhouse gases.   It then presents extensive modeling results projecting possible gas levels by 2100 under various emission scenarios. The scenarios show that global action to reduce emissions to date have been insufficient to achieve a desired goal, that of limiting the world’s average temperature increase to 2ºC (3.6ºF) above the level before the industrial revolution began.   This means that the world will have to invest in mitigation more intensively.   Only certain stringent scenarios suffice to meet this objective; other more lenient ones yield higher greenhouse gas levels that result in a temperature rise higher than the goal. If we picture the world’s energy economy as a supertanker with high inertial...