All of the estimates use different assumptions, so it's impossible to do exact comparisons. I will thus include notes about each estimate to hopefully frame them correctly.
Before you read through, my completely unscientific tldr based on reading these is that with heavy mitigation, it will cost 2-3% of our GDP annually, and without mitigation, it will cost 4-10% of our GDP annually. For perspective on those numbers, 1% of the world's annual GDP right now is $750 billion, and the US military costs ~$650 billion per year. Thus, you can think of 1% as the total cost of the US military.
Consequences of Climate Change Damages for Economic Growth
Source here
This analysis considers many, but not all, costs of climate change. The following are included:
This analysis considers many, but not all, costs of climate change. The following are included:
- agricultural changes
- land lost to sea level rise
- tourism losses
- ecosystem damage
- changes in energy usage
- losses due to health issues
- fishery changes
The following are not included (this list does not include everything):
- extreme weather damages
- losses associated with forced migration
- losses associated with reduced labor output due to extreme heat
- losses associated with flooding
- losses associated with lack of water
Thus, this estimate is likely significantly lower than the actual impacts. All that being noted, they project annual GDP losses of 0.7% to 2.5% by 2060 and 1.5% to 5% by 2100 and included these plots:
It's important to note that this projection does not assume extreme mitigation between now and 2060 and assumes a temperature increase of 1.5 degrees (C) between 2010 and 2060.
Climate Vulnerability Monitor
This analysis from DARA is interesting in that it includes an estimate for how much climate change currently costs us. They include a massive number of factors, and I'll just note that they're on page 23 in the source instead of listing them all here. They arrive at ~1% of GDP lost per year in 2010 due to climate change.
Going forward, they estimate ~2% GDP lost per year by 2030 due to climate change.
They also have an interesting set of estimates for the total cost of climate change if you compare it against the cost of mitigating. They find the following for the 21st century (page 20):
- no mitigation means 4% net loss in GDP per year
- extreme mitigation means 1.5% loss in GDP per year
- in-between mitigations means 2% loss in GDP per year
Stern Review
This is a very comprehensive analysis of the costs and impacts of climate change and includes a lot of potential causes. It's also extremely long, so I'm just going to note that their general conclusion (p 143 in the source) is:
- no mitigation: GDP losses of 5 - 20%
- heavy mitigation; GDP losses of 0 - 5%
If you are interested in this report but don't want to read hundreds of pages, the wikipedia page has a decent summary. It's also important to note that this is an older report, and the author has indicated more recently that he underestimated the costs since the climate has changed rapidly since then.
Climate Change in the United States
This is an analysis of how climate change will affect the United States that was performed by the EPA. For costs, it considered a large number of factors:
- losses associated with health issues
- losses associated with reduced labor output due to increases in extreme heat
- losses associated with infrastructure
- changes in energy usage
- losses associated with damage due to sea-level rise
- losses associated with droughts
- agricultural changes
- ecosystem changes
- losses associated with wildfires
- tourism changes
Some of the categories not included are (this list does not include everything):
- losses associated with forced migration
- losses associated with extreme weather
The costs they arrive at are roughly $300 billion per year in 2050 and $1800 billion per year in 2100. It is important to note that these costs assume some mitigation, so the costs with no mitigation would be higher.
The Cost of Climate Change
This analysis of climate change in the United States from the NRDC cites a cost of 3.6% of annual GDP by the end of the 21st century, and focuses on four factors that will make up half of that:
- hurricane damages
- changes in energy usage
- real estate losses due to sea level rise
- losses associated with changes in water availability
They provide a nice summary table that I have included below:
It is important to note that these projections are for us continuing what we do today.
American Climate Prospectus
This is an analysis of how climate change will affect the United States that was performed by the Climate Impact Lab. This is similar to the EPA one in a lot of ways, and includes the following factors:
- losses associated with coastal damage (both storms and sea-level rise)
- losses associated with health issues
- labor changes
- changes in energy usage
- agricultural changes
- changes in crime
Some of the categories not included are (this list does not include everything):
- changes in water availability
- inland flooding
- wildfires
- specialty crops
- health impacts from air pollution changes
Estimating economic damage from climate change in the United States
This is another analysis from the climate impact lab mentioned earlier. Unfortunately, this one is behind a paywall. However, there is a nice resource page here that contains the relevant information.
The results of this analysis are an estimate of GDP loss as a function of temperature increase, and an image is contained below:
There's not much more to pull from this one since you can just read the estimates off the graph. It's worth noting that they published a pretty popular article in the New York Times with this that you might have seen recently.
IPCC
The IPCC aggregated some of the available estimates for some of the costs of climate change. The sources in general model a small selection of the costs, and they mostly vary from 0% to 3% of GDP lost for 2.5 degrees (C) of warming. It is important to note that 2.5 degrees of warming will require significant mitigation, so this cost represents the cost with significant mitigation.
Global Non-Linear Effect of Temperature on Economic Production
This model is basically to derive a formula relating a country's GDP and its temperature profile, then project where each country will be as their temperature profile changes due to global warming. I don't like this model as it feels overly simplistic, but it was in the news a lot recently so I am including it.
They estimate total losses of ~23% of global GDP by 2100. They have several figures, but I am including this one that is a projection for each country. Note that this analysis shows Europe doing extremely well while many do not.
An interesting take on this model is The Price Tag of Being Young which applied the results of the model to median earners to estimate the total loss in wealth over their lives. They arrived at the following estimates of wealth loss due to climate change:
An interesting take on this model is The Price Tag of Being Young which applied the results of the model to median earners to estimate the total loss in wealth over their lives. They arrived at the following estimates of wealth loss due to climate change:
- 21 year old that goes to college: $187,000
- 21 year old that does not go to college: $142,000
- 2 year old that goes to college: $764,000
- 2 year old that does not go to college: $581,000
Summary
As you can see from these projections, there is a lot of variability in what's available. It is very difficult to do an apples to apples comparison between them since they all use different methodologies, assume different emissions scenarios, and leave out different factors.
It is very important to note that none of these analyses include all possible factors and the majority of them note that they are underestimates. Thus, it seems unlikely that the cost will be on the low end of these projections. A huge one that I couldn't find anywhere that's probably impossible to estimate well is the cost of wars associated with global warming. With agricultural output changing, countries flooding, and massive numbers of refugees/migrants, wars due to climate change seem inevitable.
One really nice summary that I did not include because it basically references other ones here is an analysis by Citigroup. However...it is worth calling it out because it's very comprehensive and they include an analysis of the cost of mitigating vs the cost of not. They find that we save tens of trillions of dollars if we mitigate.
One really nice summary that I did not include because it basically references other ones here is an analysis by Citigroup. However...it is worth calling it out because it's very comprehensive and they include an analysis of the cost of mitigating vs the cost of not. They find that we save tens of trillions of dollars if we mitigate.
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