On this Earth Day, with all the wonderful Earth Day festivals and activities and speeches that have united and invigorated us, the only thing that actually counts is reduction of greenhouse gases to stabilize our climate system. If you want to get straight to the action part and bypass the scientific rationale, skip forward to this symbol *** several paragraphs later.

To prevent the worst impacts of climate change, we must live within a carbon budget. Let’s unpack our planet’s budget, which (per page 21 of the most recent IPCC report) is stated as follows. “To have a 50% chance of preventing global warming of more than 1.5^oC, our carbon budget as of January 1, 2020, is 500 gigatons of CO₂e.”

Now that’s a lot of unpacking to do. We all understand that every bit of warming above 1.5^oC will add significantly to the harms we are already experiencing. Millions of species are at stake, arctic summer ice is at stake, low-lying countries and cities are at stake, geopolitical unrest and massive migration are at stake, crop failures are at stake, destructive weather is at stake… so even though a 50% chance doesn’t sound too attractive, let’s grab it to stave off the worst. It is practically impossible to manage with a smaller budget than 500 gigatons, so 50% seems like the best we can hope for.

What is a carbon budget at an instant of time? It is the cumulative CO₂ equivalent that we can emit from that point of time until eternity. Stated differently, it is the cumulative CO₂ equivalent that we can emit from that point of time until we achieve net zero once and for all.

Humanity emitted 59 gigatons of CO₂e in the year 2019 (see page 4 of the IPCC AR6 Synthesis Report). At this rate, our goose would be cooked by June of 2028. How old will you be then? Your loved ones? Your children? Your grandchildren?

It is clear that we need massive reductions to stay within the budget. How massive? My previous blog makes it clear that the following recipe is our only chance: “2/3 reduction by 2030, net zero by 2040.”

From a macroeconomic perspective, there are some activities that simply will not get decarbonized by 2030 either because we don’t know how, or it is too expensive. Examples: cement, steel, airplane travel, shipping. There’re also some methane emissions, land use emissions and food requirements that are inevitable. Also, the most recent United Nations plea calls for wealthier nations to decarbonize at a faster pace than developing nations – so there is a higher bar. The simple conclusion is, “Whatever we know how to decarbonize, we must decarbonize in this decade.”

It is very important to understand that carbon reduction early in this decade is worth its weight in… err… carbon! If I give you a monetary budget from now till 2030, it is of very little use to tighten your belt in 2029 – your budget will be blown by then. But reducing recurring expenses now will make all the difference over the years. So it goes with your carbon budget.

*** This is where you come in. We desperately need you to be a “Climate Champion” in calendar year 2023. The definition of a Climate Champion is simple: someone who weans his or her household off of fossil fuels, with some small exceptions, which I will get to shortly.

Being a Climate Champion requires the following:

• Day-to-day transportation is by electric vehicles, walking, biking, e-biking or public transportation.
• Home heating is electric (i.e., heat pumps).
• Cooking, clothes drying, and domestic hot water are electric.
• Backup generator (if any) is replaced by batteries or eliminated.
• The electricity you consume is 100% clean either via Community Choice Aggregation (CCA) or a clean Electricity Service Company (ESCO) or community solar or your own rooftop/backyard solar panels.

In the interest of practicality, the small exceptions are as follows:

• The public transport used may not be 100% clean (e.g., the bus or train you use for commuting) – but that will “automatically” get better over time as all of society decarbonizes.
• Use of propane or charcoal for grilling, and gas for lawn care equipment are de minimus from a carbon perspective (lawn care equipment causes harmful particulate emissions which are not the subject of this blog, we are looking exclusively at carbon here).
• Essential airplane travel, provided the resulting carbon is offset (see Carbon Fund, for example).
• Burning wood in a fireplace or wood pellets in a stove, since that wood absorbed carbon in its lifetime as a tree.
• You cannot be held responsible for carbon emissions at your workplace, although you can play a role in lobbying your employer to rapidly decarbonize.
• Use of a taxi or rental car when you travel, until e-transport is more ubiquitous.

What about composting, recycling, planting trees, diet changes, rewilding your yard, avoiding plastic, reducing waste, pollinator pathways and the like? These are excellent activities that solve other problems, but from a purely greenhouse gas perspective, they do not move the needle sufficiently. The graph below shows the amount of effort required to achieve 10 tons (horizontal axis) of annual CO₂e reduction.