So how are we doing? We’ve been talking about mitigating climate change for literally decades, and the world is currently meeting for the 27th climate summit, COP27. It feels like all we get is dire news about how miserably we are collectively failing to do anything about climate change, but the real news is actually mixed. In some ways we are better off then we were 1-2 decades ago, in others things are worse. Let’s review.

The good news is that the projection of how much the climate will warm on average is better today than it was a decade ago. Warming is measured as the average temperature increase above pre-industrial levels, usually expressed in Centigrade. Right now we are at 1 degree C above baseline. A decade ago if you looked at projections as to where we were headed, the “business and usual” projections were for 3-4 degrees C by the end of the century. Today, the same projections predict only about 2.4 degrees. Business as usual means that we keep going the way we are, including already funded pledges from countries for action to mitigate CO2 release.

It’s also not hard to do better than 2.4. A recent study published in nature extrapolates climate change for a range of scenarios, starting with what they call nationally determined contributions (NDC), which are essentially pledges as of COP26. This is one step beyond business as usual because it includes all pledges, even those not yet funded. They also consider peak warming and warming by 2100. If we reduce greenhouse gas (GHG) emissions temperature will eventually come down, as the effect of GHGs is not permanent. The NDC scenario has peak warming of about 1.8 degrees, but then coming down to about 1.7.

They also include a range of models, from various degrees of NDC to NDC+ and NDC++, including greater mitigation efforts sooner. In the NDC+ range warming will peak at 1.6 but then come down to 1.4. In the most aggressive scenario, NDC++ we can theoretically limit peak warming to <1.5 C, which is the stated goal of the Paris agreement. This entire range of scenarios, even just the NDC where we keep already made pledges, is not horrible. It keeps peak warming below the 2.0 C level where we think the inflection point is for irreversible (on a human timescale) negative consequences.

When you think about it, we’re pretty close to doing what we have to do in order to limit warming to less than 2.0 C, and having temperatures stabilize at or below 1.5 C by century end. This is legitimate reason for optimism. How did we get here? Mostly through technological advancement. Electric vehicles are now a viable and cost-effective option for most people (but we still need to ramp up production, which is happening). The cost of new wind and solar has plummeted 90%, and the technologies are getting more efficient. Battery technology continues its relentless incremental advance.

But there is also general agreement among experts that relying entirely on technological advancement is not going to be enough, mainly because it will not happen fast enough. We can speed up the rate of technological advancement by investing in green technology research, which is happening but can happen faster. We also need to invest in infrastructure, mainly grid upgrades, grid storage, and recharging stations for EVs. Subsidizing early adopters of green technology also speeds up industry transition. We also need to carefully review regulations to make sure they favor adoption of green technology and don’t inhibit it. All of these things can get us comfortably in the NDC+ range, which will likely still be bad, but not catastrophic. All of these things are relatively painless, and just require investment in the future – investments that will be extremely beneficial in the long run.

Getting to NDC++ will be more difficult, and I doubt we can do it. This will require rapid decarbonization. To get there we would likely need to aggressively price carbon. Many experts think this is a great idea – fairly and properly price carbon and let industry figure out how to limit it. There just doesn’t seem to be the political will for this approach. NDC++ would also require aggressively closing coal and then natural gas power plants and replacing them with low carbon sources. This would mean building new nuclear plants, and keeping existing ones open as long as possible. That in turn would require significant streamlining of the regulatory process. We can absolutely do this if we really wanted to, but again, I don’t see the political will.

In my opinion that leaves us with the most likely outcome being in the NDC+ range – again, bad but hopefully not catastrophic. This path would require building out wind and solar as much as possible, while upgrading the grid along the way and adding what grid storage we can. It remains to be seen how much intermittent energy upgraded grids can take, but I hope at least 40-50%. For the rest we need to maximize hydroelectric, geothermal, and nuclear, with some tidal energy and biomass thrown in. At the same time we need to aggressively convert our automobile fleet to electric, which is proceeding reasonably well. We need to incentivize major industrial emitters, like the steel and cement industries, to find greener options. Converting our hydrogen production from gray or blue hydrogen to green hydrogen will help immensely as well. Oh, and stop cutting down the rainforest.

I actually think that by 2060 or so, and definitely by the end of the century, technological advancement will allow a near full transition to green technologies. They will be the best option, adopted by default. But how quickly we get there absolutely matters, so we need to focus on which policies and investments will get us there as quickly as possible. We also will definitely need some carbon capture technology. Right now we’re mostly waiting for the research to advance, in the meantime we can maximize the number of trees in the world.

Now for the bad news – while the projected temperature range has decreased with advancing technology, our scientific understanding of the effects of different temperature increases is heading in the wrong direction. So while 2.4 C, for example, is much better than the 4 C projections of a decade ago, the effects of 2.4 C are likely worse than we thought. It now seems really critical that we keep peak warming below 2.0 C, and as close to 1.5 as possible. For example, it turns out we were vastly underestimating the amount of Greenland ice loss, and therefore resulting sea level rise. Also, warming is not uniform. The US is warming more than the global average, with a significant increase in costly weather events.

The biggest problem is that scientists can only estimate where the real tipping points are. A tipping point is an amount of warming at which an irreversible consequence will occur, or an effect will kick in that will cause further warming, leading to a cascade of locked-in warming. The biggest tipping point is the large land-based ice sheets, primarily Greenland and the Antarctic. At what point will warming lead to so much ice melt that these ice sheets become unstable and eventually collapse? That would be catastrophic, with high sea level rise and devastation to coastal cities.

Most worrying, the latest estimate is that there are potentially six tipping points which may be triggered by warming >1.5 C – including collapse of the Western Antarctic ice sheet, collapse of the Greenland ice sheet, shut down of the Atlantic conveyor belt, die off of corals, and loss of ice from the Barents sea. These all can happen somewhere between 1.5 and 2.0 C. It is therefore vital that we keep below 2.0 C or we are essentially guaranteed to hit one or more of these catastrophic tipping points, but if want want to guarantee that we trigger none of them we have to stay below 1.5 C. Again, I think this is unlikely, so we are essentially going to throw the dice with peak warming somewhere in the 1.7-1.8 range.

If I had the power to make one change to improve our chances what would it be? I actually think we are headed in the right direction with most green technology, and we just need to strengthen our pledges a little bit and keep them to achieve what these technologies can. The big thing that is missing that would be the extra piece needed to keep us below 1.5 C, in my opinion, is nuclear power. Unfortunately there isn’t much of a political appetite for it, so it is at best a climate change afterthought. But if we want to stay below 1.5 C, while we are doing all the other things, we need to replace existing coal and natural gas as fast as possible with new nuclear.

Ironically, the environmentalists really screwed the environment with their anti-nuclear campaign. We lost precious decades, and burned a lot of coal we didn’t need to. Republicans are not off the hook for this either. They wasted everyone’s time with their ridiculous climate change denial and pro-fossil fuel pandering. If instead they pursued a science-based, free market, conservative solution they would have championed nuclear power. They could have also promoted other free-market solutions to accelerate switching to green technology. Instead they chose pseudoscience and denialism. We are where we are now because of failure across the political spectrum.

But it is (just barely) not too late. There is still a small window in which we can set aside ideology and take the optimal path to rapid decarbonization. I harbor a tiny flicker of hope we can do it. But I know that realistically we are headed likely for somewhere between 1.5 and 2.0 C warming (and that is if things continue to go well). So it looks like we are going to roll the dice and see what happens.