Lukewarming After 2100

This short series has tried to detail observed impacts of climate change to date and project the extent of anthropogenic contributions to warming through the end of the century. As we have seen, it appears that impacts to date have been modest. I discussed why I think the current static period in temperatures may last another decade, to be followed by 0.5C in temperature rises ending by mid-century. Another 25-year lull follows and then we get hit by a large and rapid rise of about 1.5C between 2075 and 2100.

I’m not a scientist and this scenario is nothing more than an inexpert model driven more by energy consumption and observation of temperature rises since 1880 than other factors. Take it with a full salt shaker–I do. I only present it as a plausible scenario.

I’ll finish the series by discussing our contributions to global warming and the climate’s reaction to those contributions after 2100. I have two major points to make:

  • Our contributions to all forcings–CO2 and equivalents, land use, deforestation, etc.–will start to decline in 2075
  • Although climate will continue to change, it will take the reins back and make such changes for its own good reasons after 2100

As the IPCC and other organizations have always noted, one of the primary drivers of CO2 emissions has always been human population growth. And human population is predicted variously to reach its peak at between 9.1 billion and 9.5 billion people sometime between 2050 and 2075. Population is then expected to decline slowly.

This will reduce many of the impacts human have on the environment overall and the climate specifically. We will no longer expect to see eye-popping growth in energy consumption, use of cement, deforestation, etc.

A number of what I call ‘2 percent solutions’, which we have turned to over the past 25 years in our efforts to innovate our way out of global warming, will have had enough time to grow into their shoes by the end of the century.

Specifically, what I also nickname ‘Asterisk’ solutions which have been growing at a dramatic pace will continue to do so and will provide much of the energy we need without emitting CO2.


In the chart above, the growth of delivered solar power looks dramatic, but it has yet to reach 1 quad a year–it’s small beer for a world that consumes about 530 quads annually, and which I predict will need 3,000 quads every blessed year starting in 2075.

But what the chart doesn’t show, as it starts in 2001, is that solar power has been growing at a dramatic rate since 1978 and that rate is not expected to slow down any time soon. Solar power will continue to become less expensive, more effective and accepted and it will spread.

Solar has consistently grown at a rate of about 37% annually since 1978–by consistent I mean that if you look at almost any five-year period during that time, growth has been roughly about that. But it grew from nothing and it still is an asterisk in energy figures–it delivered about 0.1 quads last year.

If we arbitrarily decide that growth in solar will slow down by 50% and watch it grow until 2075, solar alone will deliver 2,862 quads out of the 3,000 I have estimated we will need. That’s the magic of compound interest.

My picture of the future doesn’t include space tourism or Jetson personal skycars–although I wouldn’t object to either. It does include a fleet of vehicles powered by electricity (we’ll need better batteries, but they’ll come some time this century) charged by solar power throughout most of the world. Solar will also provide much of the electricity for home office and residential use. We’ll also have wind where appropriate and a growing number of nuclear power stations.

The world will continue to urbanize, with up to 80% of the population living in cities or their suburbs. This will reduce our impact on the remaining 95% of the land–deforestation will reverse, as it already has throughout the developed world, road-building will slow down, cement use will taper off–most of the things we are doing full-bore right now that generate emissions will be either stable or declining by 2075.

But it will take until the end of the century before our impacts show up in the statistics. There is a lag between emissions and their effects on the climate. The carbon sinks that absorb CO2 will eventually suck it all in, but they work at their own pace–a pace we really don’t understand very well–and it will take time to clear the air.

The world will be a lot richer and will be able to afford the changes I detail above. (That’s a precondition of all the estimates about global warming, by the way, not just mine. If we don’t get a lot richer, we won’t be emitting all this CO2 in the first place.) There will still be the poor among us (and I’ll bet it will still be a Bottom Billion, there to spur us on to continue to help), but most people in 2075 will be richer than Americans are today–from  Chile to Vietnam.

If that turns out to be misguided optimism, we in fact will solve our problem with CO2 earlier–simply by being too poor to emit the gas that helps raise temperatures.

We will have the money. We have the technology already. If solar falters, then wind, nuclear power and some invention between now and then will take up the slack.

Those who are heavily invested in gloomier forecasts will be quick to label me as a Cornucopian techno-optimist–and they may well be right. But as others have been quick to point out, well, so what? Techno-optimism has a much better record in predicting the future than Malthusian doom-criers, or even sober realists who try and temper our enthusiasm. We may get the details (jet cars, space tourism) wrong–but the broad sweep of history looks far more like our vision than that of Thomas Malthus.

What I’m essentially arguing here is that those most concerned with climate made a mistake in characterizing anthropogenic global warming as a planet-threatening crisis that had to be solved in our generation. I argue instead that it is a century-long struggle that requires our attention and resources throughout the century–but it is a struggle I am convinced we will win.

In my opinion that is the real definition of a Lukewarmer…

12 responses to “Lukewarming After 2100

  1. On its “own good reasons” the climate has given us huge ice ages. When (not if) we fell into a major ice age, the impact on humans and other forms of life on Earth would be much harsher than all but the least credible of the AGW scenarios.

  2. Tom, ” I really don’t think generating additional heat would pose much of a challenge for us…” so you are a closet skeptic after all.

  3. Tom, Pielke, Jr. has a post on energy access which is relevant to your earlier thoughts on energy consumption growth.

  4. Brave predictions for 2075 on, my father was born 1904, lived to see what we currently call technologically enhanced civilization.
    Do you believe the next 50 years will be just like the last?

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