Attributing Current Climate Change to Specific Sources

Climate activists tend to skip over this part of the program, fast forwarding to policies to reduce emissions.

They’re furious at the recent movement in favor of ‘Fast Mitigation,’ many adherents of which think that we can reduce warming by 0.5C by the end of the century by focusing on deforestation, black soot and complex fluorocarbons. As even the most ambitious program to limit CO2 emissions will only reduce warming by 20% of that figure, the Fast Mitigation movement seems attractive.

However, both sides need to understand and (hopefully) agree on what is actually contributing to the current warming. We know that, for example, a strong El Nino can push temperatures up quickly and La Nina can sometimes (not always) erase those gains. Both skeptics and alarmists tend to forget that and other sources of natural variability when the current stats break in their favor.

This is how the IPCC viewed it in 2007:

2000px-Radiative-forcings.svg.png

This chart looks like the Fast Mitigation strategy might be able to have the impact proponents claim for it. If we could reduce Halocarbons to close to zero and black carbon, we would remove a lot of the forcings claimed for our existence on this planet.

But I don’t see on this chart anything to do with deforestation. And I don’t understand why land use is lumped in with black carbon on snow.

This chart, from Southwest Climate Climate Change (and sourced from UNEP), shows more detail. But no numbers. (When I make a chart I try to put the numbers on top of the bars. It really helps.)

radiative_forcing.preview

I’d like to see a stacked bar chart with percentages for each.

Anyone know where I can find one?

3 responses to “Attributing Current Climate Change to Specific Sources

  1. The energy imbalance we can measure using ocean heat content changes is about 0.5 watts per m2. If that chart is right, there’s a missing piece somewhere.

    • Fernando,

      Radiative forcing is the imbalance that would result if there were no temperature change. The difference between forcing and actual imbalance is increased emission due to increased temperature.

  2. Tom,

    You wrote: “But I don’t see on this chart anything to do with deforestation.”
    That affects both CO2 and albedo.

    “And I don’t understand why land use is lumped in with black carbon on snow.”
    Well, it says right on the chart “Albedo”. But it should be “”Surface albedo” since aerosol effects also alter albedo.

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