Good afternoon, and welcome to another climate briefing from ScholarTribe. In the news over the past week - governments across the world continue to sever ties with Russian hydrocarbons; both the North and South pole have been hit with temperatures over 30 degrees higher than normal (link), and a Saharan dust cloud has made Europe marginally more orange.
In the world of research however, this is what we will be covering:
đ Heat pumps vs Hydrogen
đ The IPCC Working Group 3 report
đł Amazon rainforest resilience
đ âŠand weâll also give you a bite-sized primer on methane!
Pump it (Louder!)
Heat pumps have been rapidly gaining in popularity for a few years now, almost to the point where people actually know what they are. To set the record straight, they basically work as reverse fridges, using ambient outside air to heat indoor radiators or boilers. They are overall preferable to current means of heating, as they are powered purely by electricity, which can come from renewable sources, or at the very least from more efficient burning of fossil carbon on the grid. According to the International Energy Authorityâs net zero pathway, we will need to install 1.8 billion pumps by 2050 across the globe, which is ten times the number we have now.
Heat pumps are compared to hydrogen, another cleaner heating method, in a new briefing paper from Imperial College London. They say that heat pumps are highly efficient and clean when powered by renewable electricity, but are less familiar to consumers, and would be quite difficult to roll out quickly. Hydrogen, on the other hand, has no CO2 emissions at the point of use, but it is expensive to produce hydrogen in a low-carbon manner (âgreenâ and âblueâ hydrogen are a topic for a future editionâŠ). The main advantage of hydrogen is that to a consumer it would more or less feel like using a natural gas boiler, and also the existing gas grid could be adapted to deliver it to homes.
The final recommendations from the authors are that, on balance, heat pumps should be focused on in the near term for most domestic settings, and hydrogen should instead be reserved for those sectors which are hard to electrify. The authors also encourage more government financing schemes and grants, as well as recommending that manufactures of complementary technologies, such as air conditioning, diversify to heat pumps.
The full briefing paper from Imperial can be found here
Youâre joking, not another one?
"We have a lot more material, this time on carbon dioxide removal. That is, not putting carbon into the atmosphere, but getting it out again" - Prof Jim Skea, Imperial College on the WG3 report
We wrote about the working group 2 report in the last edition of this briefing, but already we have number 3 on our hands. Right off the bat, one of the key headlines of the report is that, with current mitigation policies only, we are on track for temperatures to level off at +3 degrees, which is clearly well above the preferred +1.5 degrees of the Paris agreement.
After discussing the extend of this problem, the report then goes on to describe some possible roadmaps (called âemissions pathwaysâ) towards 1.5 degrees, which involve lots of different mitigation techniques such as carbon capture and storage (CCS).
There are many different approaches to CCS, from natural methods like reforestation all the way to direct air capture. Critics of CCS say that it is a lazy way to avoid the necessary changes to society which are required of us, and they also raise concerns that some methods of carbon sequestration are non-permanent. However, it is an unavoidable fact that we can only reach net zero when the total tonnes of carbon emitted into the atmosphere per year are equal to the tonnes of carbon captured and stored per year. The report even goes so far as to suggest that once net zero is reached, we might want to go net-negative, to reverse as much of the planetâs warming as possible. And to do that, we will absolutely need CCS.
A link to the summary for policymakers
On the precipice
A new paper, published in Nature Climate Change, is all about the looming tipping point in the Amazon rainforest, and how the rainforestâs declining resilience is moving us ever closer to that point.Â
The resilience of the rainforest is defined as how quickly it can return to equilibrium after an extreme drought or heat event, which is something that is crucial for both the local climate and the global carbon cycle. The study shows that around three-quarters of the rainforest has seen a drop in resilience over the last couple of decades, and this three-quarters is disproportionately grouped around areas of human land use.Â
This is worrying to the authors, who say that if this trend continues, we may see irreversible damage to one of the worldâs big carbon stores. This is because the Amazon sustains its own regional climate, where water is effectively recycled upwards into rain clouds. This reduces the length of any dry seasons, and lowers the chance of fires. If this system is interrupted, however, we may see the most vulnerable parts of the forest become permanent savannah, leading to ecosystem loss and the release of all that stored carbon.Â
The research paper can be found here
Physical Climate Demystified - Methane
If you ask anyone off the street to name two greenhouse gases, youâll probably get the same two answers - carbon dioxide and methane. A few people might say water vapour or nitrous oxide, but for the most part theyâll be going with the big two.Â
But what about if you ask what the difference is between carbon dioxide and methane? People will tend to know that methane comes from burping cows, and might vaguely remember that methane is more potent than carbon dioxide. But the most crucial difference is missed by most, and that is to do with how long the two gases persist in the atmosphere.
Carbon dioxide stays in the atmosphere for ages. Every additional tonne of CO2 that is added to the atmosphere contributes a long-lasting warming effect. This is why we have the idea of the carbon budget - a known amount of emitted CO2 will result in a warming of 1.5 degrees. You add carbon, you raise the temperature - simple.
Methane, on the other hand, only lasts for about a decade or so, as chemical reactions in the atmosphere break it down. This means that if you release one tonne of methane, it will only provide a warming effect for 10 years. This is important to understand, because it means that it is the rate at which methane emissions change that is important.Â
So, some parting thoughts - should current methane emitters be more readily incentivised to downscale? And should we only tax increases in methane production? What about offsets - how do we go about offsetting methane emissions with CO2 removal, when clearly there can be no direct conversion between the two? Big questions, I hope you agree.Â