If we immediately stopped emitting greenhouses gases, would global warming stop?

July 2, 2007

Not right away. The Earth’s surface temperature does not react instantaneously to the energy imbalance created by rising carbon dioxide levels. This delayed reaction occurs because a great deal of the excess energy is stored in the ocean, which has a tremendous heat capacity. Because of this lag (which scientists call “thermal inertia”), even the 0.6–0.9 degrees of global warming we have observed in the past century is not the full amount of warming we can expect from the greenhouse gases we have already emitted. Even if all emissions were to stop today, the Earth’s average surface temperature would climb another 0.6 degrees or so over the next several decades before temperatures stopped rising.

The time lag is one reason why there is a risk in waiting to control greenhouse gas emissions until global warming becomes worse or its effects more serious and obvious. If we wait until we feel the amount or impact of global warming has reached an intolerable level, we will not be able to “hold the line” at that point; some further warming will be unavoidable.

  1. References

  2. Hansen, J., Sato, Mki., Ruedy, R., Kharecha, P., Lacis, A., Miller, R.L., Nazarenko, L., Lo, K., Schmidt, G.A., Russell, G., Aleinov, I., Bauer, S., Baum, E., Cairns, B., Canuto, V., Chandler, M., Cheng, Y., Cohen, A., Del Genio, A., Faluvegi, G., Fleming, E., Friend, A., Hall, T., Jackman, C., Jonas, J., Kelley, M., Kiang, N.Y., Koch, D., Labow, G., Lerner, J., Menon, S., Novakov, T., Oinas, V., Perlwitz, Ja., Perlwitz, Ju., Rind, D., Romanou, A., Schmunk, R., Shindell, D., Stone, P., Sun, S., Streets, D., Tausnev, N., Thresher, D., Unger, N., Yao, M., and Zhang, S (2007). Dangerous human-made interference with climate: A GISS modelE study. Atmospheric Chemistry and Physics, 7, 2287-2312.
  3. Hansen, J., Nazarenko, L., Ruedy, R., Sato, Mki., Willis, J., Del Genio, A., Koch, D., Lacis, A., Lo, K., Menon, S., Novakov, T., Perlwitz, J., Russell, G., Schmidt, G.A., and Tausnev, N. (2005). Earth’s energy imbalance: Confirmation and implications. Science, 308, 1431-1435. doi: 10.1126/science.1110252

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