The climate’s response to energy changes takes decades

  • 16 Feb 2012, 18:05
  • Verity Payne

If the world switched from coal-fired power to low-carbon energy there would still be a hiatus of around fifty years before greenhouse gas emissions reduced and temperature stabilised, according to new research. What's more, switching to natural gas is unlikely to benefit climate over the coming century.

Researchers Nathan Myhrvold, of Intellectual Ventures, and Ken Caldeira of the Carnegie Institution for Science, used basic mathematical models to calculate how much greenhouse gas emissions and global average temperature might change over the coming century if we switch to low-carbon power sources. The green energy measures considered are hydroelectricity, solar, nuclear, wind, natural gas, conserving energy where possible, and carbon capture and storage.

The research, published today in the journal Environmental Research Letters, suggests that a transition to low carbon energy will initially cause greenhouse gas emissions to rise compared to coal power. This is because setting up the green power plants will result in greater greenhouse gas emissions than using existing coal-fired plants.

With new green power plants under construction - which would increase emissions in itself - we would also continue to use coal energy, thus adding to existing emissions. Once up and running, however, the green energy plants emit far fewer greenhouse gases.

Myrhvold explains:

"You have to use the energy system of today to build the new-and-improved energy system of tomorrow, and unfortunately that means creating more emission in the near-term than we would otherwise. So we incur a kind of 'emissions debt' in making the transition to a better system, and it can take decades to pay that off. Meanwhile, the temperature keeps rising."

The delay in climate benefits of green energy would also be compounded by the 'thermal inertia' of the oceans - which means the oceans take a while to release any heat they contain.

The research hasn't yet received much media coverage, apart from in the Mail Online, which rather predictably misinterprets the paper with the headline: Switch to low-carbon power sources 'risks making global warming worse' study warns.

In fact in the long term  - after around four decades for solar wind and nuclear power - low-carbon energy sources will reduce global warming.

Switching to natural gas won't benefit climate this century

The researchers also found that switching to natural gas simply delays inevitable warming. They write:

"Conservation, wind, solar, nuclear power, and possibly carbon capture and storage appear to be able to achieve substantial climate benefits in the second half of this century; however, natural gas cannot."

So although natural gas is often touted as the best way to bridge the transition to low carbon energy it is not likely to achieve greenhouse gas and temperature reductions this century.

Delaying switch to green energy 'risks even greater environmental harm'

The researchers warn that we should switch to low-carbon energy sources sooner rather than later. They write in the research paper:

"... Delaying rollouts of low-carbon-emission energy technologies risks even greater environmental harm in the second half of this century and beyond."

As Caldeira puts it:

"There is no quick fix to global warming. Shifting from one energy system to another is hard work and a slow process. Plus, it takes several decades for the climate system to fully respond to reductions in emissions. If we expect to see substantial benefits in the second half of this century, we had better get started now."


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