Sometimes I’m asked questions like “how soon do we need to reduce our global warming emissions?” or “how much time do we have before climate change gets really bad?”
These questions always surprise me—it’s a bit like a smoker asking a doctor “how soon should I quit?” The only correct response is “don’t wait, you should quit as soon as possible.” Recent science and new developments have highlighted the urgency of reducing global warming emissions to “net zero” as soon as possible.
It’s my job to pay attention to what’s happening on the climate science and policy front, and nowadays the volume of information makes it hard for me to keep up. Every day, it seems that there is a new groundbreaking study, another record broken, a new dire threshold approached, or a new innovation announced that brings us closer to solutions.
In the past few months, things that seemed far out of reach just a few years ago—including the possibility that we could reduce our total emissions to net zero within a few decades—now seem not only possible, but absolutely necessary.
“Net zero” emissions means that all the sources of heat-trapping emissions (such as burning fossil fuels) would be in balance with all the processes that remove heat-trapping gases from the atmosphere (such as the growth of forests).
A balanced financial budget makes good sense for a household, and a balanced carbon budget makes good sense for the planet—in fact, it’s a fundamental part of our climate strategy. Nevertheless, since the advent of the Industrial Revolution, the world has been far overspending its carbon budget, and the result has been a rise in the concentration of heat-trapping gases and a consequent rise in global temperatures.
For everyone who doesn’t spend their days tracking climate science and policy, here’s a short list of some of the many reasons why we need to bring our emissions to net zero as quickly as possible.
1. Our current path will lead to irrevocable changes to the climate system and sea levels that will last for several thousand years.
An article in Nature Climate Change (paywall) recently looked far into the future, asking the questions “how long will climate impacts continue, and what will they look like?”
Most of the results reported from climate modeling efforts look at scenarios through the year 2100, but this analysis looked 10,000 years into the future—and the results were staggering. On this time scale, the effects of climate change are driven by the cumulative emissions of human activity, and the longer we emit heat-trapping gases, the more severe the future changes.
For higher levels of cumulative emissions (in line with our current trajectory), “the resulting sea-level rise reaches as much as 45 m [about 150 feet] in 10,000 years” just from the loss of the Antarctic ice sheet alone. Contributions from the Greenland ice sheet and other sources could add several more meters.
The implications are difficult to fathom. Most of Florida would be underwater, and the Mississippi delta would be inundated north of the Louisiana-Arkansas border. Around the world, ancient cities like Cairo and Shanghai would disappear. Coastlines would shift dramatically, and low-lying countries like Bangladesh would face drastic reductions in area.
Where will future populations reside? How will they think of their history—and today’s legacy—when parts of cities like London, New York, Tokyo, and Mumbai are lost to the rising waters? According to the article, “The only means to prevent a further commitment to [global mean sea level] rise is to achieve net-zero emissions.”
The maps show areas of submergence for countries with at least 50 million people living on land affected by long-term sea level rise projections, including large municipal areas. Source: Clark et al. 2016.
2. If we reduce our emissions, we’ll feed more hungry people and save more lives.
A recent modeling study in The Lancet looked at a shorter time horizon, examining the impacts of climate change on human health over the next few decades. The focus of the study was on global food availability and induced changes in consumption patterns.
The overall results were positive: in almost every area of the world, projections showed that more food and greater nutritional quality would be available. But climate change created a drag on our progress toward alleviating global malnutrition and hunger, resulting in more than half a million climate-related deaths worldwide by 2050. These are deaths that would have been avoided in the absence of climate change. We’re on track to produce more food of higher quality, but climate change will undercut our efforts, jeopardizing the global goal to eliminate hunger by 2050.
The map shows the change in the frequency of climate-related deaths projected to occur by 2050 as a result of climate disruptions to the global food system. Source: Springmann et al. 2016
3. We should follow through on our global commitments—besides being worthwhile in themselves, they’re likely to strengthen other areas of progress, too.
The UN climate agreement reached in Paris in 2015 marked a turning point in international efforts to combat climate change. There were many high points to illustrate, but the most fundamental shift was that nearly every country agreed to take some level of responsibility for addressing the problem.
We are now all in the same boat together, paddling toward a common goal of avoiding disruptive climate change, captured in the agreement as “Holding the increase in the global average temperature to well below 2 °C above pre-industrial levels and pursuing efforts to limit the temperature increase to 1.5 °C above pre-industrial levels.”
“In order to achieve the long-term temperature goal,” the agreement says, countries will “aim to reach global peaking of greenhouse gas emissions as soon as possible … and to undertake rapid reductions thereafter in accordance with best available science, so as to achieve a balance between anthropogenic emissions by sources and removals by sinks of greenhouse gases in the second half of this century….” In other words, all countries will work to reach net zero emissions sometime after 2050.
The US and China were key to the agreement, as the two countries with the largest annual emissions. The path to reaching agreement in Paris was paved well in advance, through months of diplomatic efforts on both sides, culminating in a joint announcement that sent far-reaching signals other countries.
Now that countries have put their commitments on the table, we could see a snowball effect of cooperation. Countries that make progress on their own could find that their efforts would be amplified through cooperation with others. This could come in the form of sharing expertise, collaborating on technology, or harmonizing terms of trade. All of these examples could have positive spillover effects, such as boosting food security, accelerating electrification, or preventing “leakage” of emissions through trade.
4. Decarbonizing our economy is a path to innovation, rather than stagnation.
In past international climate negotiations, I used to hear countries talk about the “burden” of reducing greenhouse gas emissions, and how the costs of reductions would put countries at an economic disadvantage relative to those who continued to emit. In fact, this kind of thinking drove the Byrd-Hagel Resolution in 1997, which helped to justify the US pulling out of the Kyoto Protocol.
Now, I don’t hear that argument much, and a recent article may illustrate one reason for this change: more than 20 countries—including the US—are using policies to actively push down the carbon intensity of their economic growth—the so-called “decoupling” of emissions from economic growth (though the complexities of the relationship might mean a “slipping clutch” is a more accurate metaphor).
The more progress they make, the more it means that emissions reductions are no longer a perceived obstacle for economic growth. The successful countries cover a range of scales and economic circumstances—from economic powerhouses like the US and Germany, to those that are still emerging or have recently weathered troubles, like Romania and Portugal. Thus, it is clear that countries at all levels of development can turn their economies away from high-emissions pathways without fear of losing their competitive edge.
In fact, they may actually gain an economic edge. In country after country, I’m hearing many people quietly say that a transformation is underway, and that once it is complete, there will be no going back. The transformation involves recasting economic development plans so that they don’t create dependence on high-emissions approaches. This was the approach undertaken in the European Union, Northeast states participating in the Regional Greenhouse Gas Initiative, and the economy-wide cap on emissions in California.
These many examples are a testament to economic growth in the context of falling emissions. Colleagues in these countries tell me that taking high-emissions pathways off the table actually spurred innovation, new technologies, and new economic opportunities. The same thing is happening in the US, but it is uneven across the country. We need an approach that can help lift all boats —starting with those that currently face the most difficult economic challenges, such as coal country and other vulnerable communities.
5. We’ll take better care of our land.
If emissions continue, we will see serious and ongoing disruptions of ecosystems we care about and depend upon.
This was illustrated in a recent paper (paywall) that looked at the tolerance of forests to an array of climate-related stressors, especially drought. Using the most recent family of climate change scenarios, the authors found that our emissions matter for the future of our forests. Their approach corroborated what others have found, including projections for the Rocky Mountain states.
However, one surprise was that Northeastern forests were found to be especially vulnerable to the drier conditions expected with high emissions of heat-trapping gases. Many of us had expected the forests in that part of the country to fare relatively well, and to continue to deliver the much-needed service of absorbing carbon from the atmosphere. This study suggests that those expectations may have been too rosy.
Disturbingly, the paper also projects that some ecosystems across the south and in the Pacific Northwest will be replaced by entirely new ecosystems not currently found in the US. Are our universities training today’s students to manage such forests? Are they training them in how to manage the transition to these new ecosystems? I would guess that we are not adequately preparing for these changes.
The map shows areas where unabated climate change would cause forest ecosystems to change to types that are not currently found in the United States. Source: Lienard et al. 2016
On the other hand, we could avoid such bizarre and disruptive outcomes if we reduce emissions quickly, and better land management can actually help us accomplish that goal.
A little less conversation, a little more action please
When I look at the possibilities, it seems very clear to me that we should make every effort to reduce our emissions to net zero as soon as possible.
We can minimize damaging and irrevocable effects of climate change, save lives, strengthen each others’ successes, spur economic growth, and leave future generations with a better place to live.
The US has a key role to play, and it’s time for us to make this a priority.