Posts Tagged: feedback

This week’s top climate science links

Dive right in:

  • Why positive feedback doesn’t necessarily lead to runaway warming – Positive feedback happens when the response to some change amplifies that change. For example: The Earth heats up, and some of the sea ice near the poles melts. Now bare water is exposed to the sun’s rays, and absorbs more light than did the previous ice cover; so the planet heats up a little more. In both of these cases, the “effect” reinforces the “cause”, which will increase the “effect”, which will reinforce the “cause”… So won’t this spin out of control? The answer is, No, it will not, because each subsequent stage of reinforcement & increase will be weaker and weaker. The feedback cycles will go on and on, but there will be a diminishing of returns, so that after just a few cycles, it won’t matter anymore.
  • Himalayan Glaciers: Wrong Date, Right Message – Is the AR4 terribly flawed? It is important to note that this is one error in a roughly 3000 page technical document, an error percentage similar to the Encyclopedia Britannica. The 2035 claim was not included in the Technical Summary, the Summary for Policymakers, or the Synthesis Report. Does this error show the IPCC has an ‘alarmist’ bias – a tendency to exaggerate the negative impacts of climate change? In fact, there are far more documented instances of the AR4 being too conservative, rather than too alarmist, on emissions scenarios, sea level rise, and Arctic sea-ice melt. Many of the Himalayan Glaciers are retreating at an accelerating rate (Ren 2006) and roughly 500 million people depend on the melt water from these glaciers (Kehrwald 2008).
  • A history of international climate change policy – An overview of the history of international climate policy over the last 30 years, divided into five periods. The article shows (1) the increasing complexity of the definition of the climate change issue from an environmental to a development issue; (2) the inability of the developed countries to reduce their own emissions and raise funds commensurate with the nature of the problem and their initial commitments; (3) the increasing engagement of different social actors in the discussion and, in particular, the gradual use of market mechanisms in the regime; (4) the increasing search for alternative solutions within the formal negotiations—such as the identification of nationally appropriate mitigation actions for the developing world, reducing emissions from deforestation and forest degradation, and the use of geo-engineering solutions; and (5) the search for solutions outside the regime—the mobilization of sub-national policies on climate change, litigation, and markets on biofuels.
  • Coffee threatened by beetles in a warming world (!) – The Arabica coffee grown in Ethiopia and Latin America is an especially climate-sensitive crop. It requires just the right amount of rain and an average annual temperature between 64 degrees Fahrenheit and 70 degrees Fahrenheit to prosper. As temperatures rise — Ethiopia’s average low temperature has increased by about .66 degrees F every decade since 1951, according to the country’s National Meteorological Agency — and rains become more variable, Ethiopian coffee farmers have suffered increasingly poor yields. Last year was especially bad, with exports dropping by 33 percent. Some have moved their coffee trees to higher elevations, while others have been forced to switch to livestock and more heat-tolerant crops, such as enset, a starchy root vegetable similar to the plantain. Now, there is evidence that a warming climate may be linked to one of the major threats facing the coffee industry in Ethiopia and elsewhere…

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