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Straight Talk on Temperature: Here's What 1.5 Degrees C Means

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The massive base of a giant sequoia tree in Sequoia and Kings Canyon National Parks.
The base of a giant sequoia in Sequoia and Kings Canyon National Parks. These trees evolved to survive wildfire, but high-intensity wildfires last year are estimated to have killed thousands of giant sequoias. (Kiel Maddox/National Park Service)

This story is part of Covering Climate Now, a global journalism collaboration strengthening coverage of the climate story.

We are 1.1 degrees Celsius above pre-industrial levels now. Capping average global temperature at 1.5 degrees C (equivalent to 2.7 degrees Fahrenheit) is within our grasp, but it will be hard, and the window is closing. As journalists we must get this story right for our audiences. They need to understand that global temperature rise can still be stopped before it reaches a catastrophic level — that doing or not doing so is a choice governments are making. This explainer covers the importance of 1.5 degrees C, the forces standing in the way of achieving it, and what it means to live in a 1.5 degrees C, or even warmer, world. It also includes some questions to prompt story ideas and short resource lists for your reference.

Why is 1.5 degrees C such an important target?

Since the Paris Agreement was signed at COP21 in 2015, scientists have become more certain that 2 degrees C of average global temperature rise above pre-industrial levels would be cataclysmic — and that even 1.5 degrees C will be no walk in the park. The record heat that scorched the Pacific Northwest in 2021? Such heat waves are now happening five times more often after “only” 1.1 degrees C of temperature rise than they did historically, according to the UN Intergovernmental Panel on Climate Change’s “Sixth Assessment Report,” released in August 2021.

At 2 degrees C, similar heatwaves would occur 14 times more often and the historic ‘Black Summer’ fires that ravaged Australia in 2019 to 2020 would happen four times as often. Hitting 2 degrees C would also mean the loss of 99% of coral reefs — the base of the marine food chain — and assure the irreversible loss of the West Antarctic ice sheet, eventually causing 5 meters (roughly 16 feet) of sea level rise, enough to inundate large portions of many coastal cities around the world.

So 1.5 degrees C is the essential target. That said, 1.5 degrees C is not a cliff; civilization does not automatically expire if temperatures exceed that threshold. Rather, every tenth of a degree beyond 1.5 degrees C makes climate damages that much greater and the overall crisis harder to contain.


“When you get above about a degree-and-a-half, these effects start to go non-linear,” said Michael Oppenheimer, the Albert G. Milbank professor of Geosciences and International Affairs at Princeton University. “It becomes very, very difficult for humans to catch up, to adjust. And basically, there’s a risk that the climate spins out of control, beyond our ability to adjust and adapt to it.”

What will it take to limit average global temperature rise to 1.5 degrees C?

The good news is that IPCC scientists and most experts say humanity has nearly all the knowledge and tools needed to limit temperature rise to 1.5 degrees C. The challenges are not primarily technological; they are political and economic.

To cap global temperature rise there are two chief imperatives, experts have concluded: First, the global economy must quit oil, gas, and coal rapidly and shift to solar, wind, and other non-carbon energy sources. Second, humans must end deforestation, much of which is driven by industrial agriculture’s desire to expand beef, soy, and palm oil production.

Imperative 1: Energy

label='Here's What's Inside Newsom's Whopping $15 Billion Climate Plan'

Coal has been the main driver of global warming since it began fueling the Industrial Revolution in Great Britain 250 years ago. Today, coal must be phased out, starting immediately and around the world, to keep the 1.5 degrees C target within reach. Scientists estimate that 90% of today’s coal reserves must be left in the ground, according to a 2021 study in Nature. The International Energy Agency (IEA) has declared that the 1.5 degrees C temperature limit also requires that no new coal-fired power plants be built. Existing plants should quickly shift to solar and wind, augmented by reducing electricity demand through better energy efficiency in buildings and machinery (which also saves money and produces more jobs). The benefits of energy efficiency are an essential tool for slashing emissions while boosting the economy — and should be explained to the public in more depth.

Oil and gas must follow the same script as coal, though in their case 60% of reserves must be left in the ground. The IEA further emphasizes that point, stating in 2021 that meeting the 1.5 degrees C goal requires that no new fossil fuel infrastructure be built anywhere on Earth. That means no exploring for additional reserves, no new oil fields, no pipelines, no liquid gas export terminals, etc.

To prevent the world economy, which currently relies on fossil fuels for 80% of its energy, from collapsing in the process, demand for these fuels must be radically reduced. Transportation in particular must transform: Vehicles must be powered by electricity, not gasoline, and driving needs to become less necessary by redesigning cities and suburbs so residents can meet their needs with mass transit, biking, walking, etc.

Another way of describing the stages of this energy transition comes from the nonpartisan research agency, Carbon Tracker: “The world needs to decarbonize electricity, electrify everything it can, and use some variant of hydrogen for the rest.”

Imperative 2: Deforestation

The link between the food and forestry sectors is critical: A major reason the world’s forests are felled at such catastrophic rates is to grow more food products, especially beef, soy, and palm oil. Forests must be left intact so they continue to extract CO2 from the atmosphere via photosynthesis and store it in trees and soil. Alas, so much of the Amazon rainforest has been leveled that much has flipped from being a carbon sink that stores CO2 to a carbon source that emits it. Because deforestation is largely driven by a push to raise cattle and other foods, some scientists suggest that people change their diets to consume less meat. But as with calls to take the bus rather than drive a car, such individual lifestyle changes cannot fix the underlying problem as long as the global economic system demands endless growth and government policies make destroying the climate more profitable than protecting it.

Be cautious about “net zero” pledges

Beware of climate greenwashing about both energy and forests — that is, rhetorical promises by governments, corporations, or banks that claim to solve the crisis but may or may not measure up in practice. The concept of “net zero emissions” demands special attention.

“Net zero” means that a given country or company will reduce emissions but not to absolute zero; rather, some emissions will continue, but they will be “offset” by countervailing measures that extract carbon from the atmosphere so the net result is zero emissions. Examples of these countervailing measures include planting trees and restoring wetlands; both draw CO2 out of the air through photosynthesis. With CO2 atmospheric concentrations currently at 414 parts per million and rising, some CO2 extraction will be needed to return concentrations to the 350 ppm or lower needed to stabilize earth’s climate.

“Net zero” is not necessarily a dodge, but offsets have a spotty record of achievement. For example: Were the promised trees actually planted? Did they survive and for how long? Were those wetlands truly restored, or only slated to be restored? Offsets also raise environmental justice concerns, for even authentic offsets in one part of the world can enable factories to keep operating in another part of the world, polluting the local environment of residents who often are poor or people of color.

Many net-zero commitments by governments and businesses cite 2050 as the year when net zero will be reached. Indeed, roughly 80% of the world economy is now covered by commitments of net zero by 2050. It’s important to report those commitments with a degree of skepticism: 2050 is far enough off that bold claims might seem possible, but those claims are only credible if they include real (i.e., non-offsets) and substantial emissions reductions during the next 10 years. To test the validity of net-zero 2050 pledges, journalists should check whether such commitments carry an action plan that credibly cuts emissions in half by 2030. That’s essential, scientists say, to hitting 1.5 degrees C. Promising that emissions will end by 2050 is easy for today’s politicians and corporate leaders, but that goal is only reachable if actual emissions fall by half in the next decade.

How did we get here?

It will undeniably be difficult to cut emissions as much and as fast as science says is necessary, and the main reason why is that humanity waited so long to start the job. Had we begun 30 years ago, as scientists and advocates were urging, we’d be most of the way there by now. And the main reason we waited so long is that some very rich and powerful economic and political interests knew climate action would interfere with their profits and privilege.

Investigative journalism has documented that Exxon and other fossil fuel companies knew by the late 1970s — because their own scientists were telling them — that climate change was real, caused by burning fossil fuels, and threatened to end civilization as we know it. Nevertheless, the companies chose to lie to the public, policymakers, and the press to thwart climate action. Recently, the companies have shifted from outright climate denial — no longer tenable in the face of so much extreme weather — to its more presentable cousin, climate delay. But climate delay is just as lethal, precisely because 40 years of failing to act has left zero time for further delay.

Fossil fuel companies now face dozens of lawsuits from governments and civil society groups demanding compensation for the climate damages the companies’ lying helped cause.

How do we live with 1.5 degrees C?

As the extreme weather in recent years has shown, climate impacts are punishing even after “only” 1.1 degrees C of temperature rise. This is especially so for the roughly two billion people who live in the (usually poorer) countries most vulnerable to climate change. Temperatures and impacts are bound to increase in the years ahead, if only because humanity can’t halt emissions overnight.

Hence, the need for what climate experts call “adaptation”: actions to reduce one’s vulnerability to the impacts of climate change. Examples of adaptation include when a community builds sea walls to protect against hurricanes, when a homeowner plants trees around the house to shade it from extra heat, and when a farmer shifts from growing almonds and alfalfa to less thirsty crops. By contrast, “mitigation” refers to actions to limit global temperature rise, such as replacing a coal-fired power plant with a wind turbine or installing more efficient appliances, windows, and insulation to reduce the amount of energy a household uses.

Adaptation has never gotten the attention mitigation gets, perhaps because it was assumed, wrongly, that the rich could adapt relatively easily to rising temperatures. For example, the British government spent roughly $3 billion dollars to build the Thames Barrier, a set of massive floodgates downriver from central London, to protect the city from North Sea storm surges. But in fact, adaptation and mitigation are twin imperatives: Mitigation is essential to limit temperature rise to an amount humans can survive, but adaptation is no less essential; because we’ve waited so long, stronger climate impacts are now unavoidable, and the only way to survive them is to prepare.

Some of the best climate adaptation research and practice happens to be found in two of the most vulnerable countries on earth: The Netherlands and Bangladesh. The former is rich, the latter not, illustrating that wealth alone is not decisive. More important is that a country starts adapting now, rather than waiting until climate impacts engulf it.

Examples of successful adaptation abound (see CCNow executive director Mark Hertsgaard’s book “HOT: Living Through the Next Fifty Years on Earth” for specifics), but they all cost money, which is where the contrast between rich and poor does have meaning. A low-income country such as Bangladesh simply does not have the financial means as the wealthy Netherlands to adapt to a changing climate and its worsening impacts.

Which is why the issue of climate adaptation will arise at COP26 mainly in regards to the $100 billion in annual aid that rich countries have pledged to provide to poor countries. This pledge, enshrined in the 2015 Paris Agreement, is supposed to subsidize both mitigation and adaptation efforts in poor countries. Independent experts calculate that poor countries need much more than that; meanwhile, rich countries have not provided even that much. An analysis by the anti-poverty NGO Oxfam found that in 2018 (the last year with reliable data), climate aid was roughly $20 to $22 billion.

Developing countries have warned in the lead-up to COP26 that there will be no deal if rich countries don’t deliver a credible plan to deliver the $100 billion in annual aid.

How Do We Pay for 1.5C?

Money is at the heart of the climate emergency and its solutions. This is true both of public money (i.e., government) and private money (i.e., banks and investors). For many years, most public and private money incentivized climate-destructive activities. At the moment, the world’s governments provide roughly $5.9 trillion a year in subsidies for fossil fuels, according to the International Monetary Fund. The vast majority of governments’ stimulus spending to revive Covid-battered economies has reinforced the status quo rather than boosted the zero-carbon activities necessary to ensure a climate-safe future. The challenge now is to halt spending that harms the climate and redirect it to things that help it.

Judging from the Paris climate summit’s impact, COP26 also could have a profound influence on global money flows. The Paris Agreement’s pledge to transition the global economy to “net zero” emissions by 2050 sent a powerful message that public and private sector leaders have taken to heart. Three quarters of the coal plants planned or being built at the time of the Paris Agreement have been scrapped. That’s partly because solar and other alternative sources were becoming cheaper. But it’s also because government planners and private investors read the writing on the wall after Paris: Coal could only survive with massive state subsidies, and governments facing widespread concerns about climate change were unlikely to keep providing those subsidies.

A similar dynamic is playing out around fossil fuels in general. Mark Carney, the UN Special Envoy on Climate Action and Finance, was the head of the Bank of England in 2014 when he began warning about a “carbon bubble” that could crash the global economy. Preventing catastrophic climate change, Carney pointed out, required leaving most of fossil fuel reserves in the ground. But those reserves were (and still are) counted as wealth in the stock holdings of investors; leaving them unburned would render trillions of dollars of invested wealth worthless. That could spark a global financial crisis as destructive as the one unleashed when the housing bubble burst in 2008.

Some of the world’s richest investors have accordingly begun distancing themselves from fossil fuels. BlackRock, the largest money-manager on earth, said in 2020 that it would shun fossil fuels and assume the world economy was moving towards alignment with the Paris Agreement.


Now that smart money is abandoning fossil fuels, two big questions are coming into focus: How much of the market will follow? And will enough money flow to the climate-friendly technologies and practices needed to defuse the climate emergency? Again, much will depend on how strong a message emerges from COP26. Journalists should monitor what governments say they will and won’t spend on climate action — not just in fiscal budgets but also through central banks. Also key is what governments will do to encourage private banks and investors to stop funding climate destruction and instead finance climate solutions.

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