The most catastrophic outcomes of climate change can still be avoided, the IPCC says, but it will require ambitious action now
The latest report from the world's top climate scientists at the Intergovernmental Panel on Climate Change (IPCC) has outlined the remaining feasible paths to avoiding the most catastrophic impacts of global warming.
Global temperature rise can still be halted at 1.5 degrees above preindustrial levels, but achieving that will require "rapid and deep and in most cases immediate [greenhouse gas] emission reductions in all sectors". As it stands, climate policies and targets are not yet consistent with modelled pathways that have a two-thirds chance of meeting the 1.5 degree goal.
Current pledges by the world's governments "will likely exceed 1.5C during the 21st Century" and would need an "unprecedented acceleration" in emissions cuts in the 2030s to limit warming to 2 degrees. Current policies are even worse, setting the world on a path to 3.2 degrees of heating by the end of the century.
"We are on a pathway to global warming of more than double the 1.5 degree limit agreed in Paris. Some governments and business leaders are saying one thing, but doing another. Simply put, they are lying," United Nations secretary-general António Guterres said.
"This report of the Intergovernmental Panel on Climate Change is a litany of broken climate promises. It is a file of shame, cataloguing the empty pledges that put us firmly on track towards an unliveable world."
The report is the third and final in the IPCC's sixth round of assessing global climate science. The first, released in August, canvassed the evidence for and mechanisms behind our changing climate. The second, from February, looked at the impact of climate change on human society and natural ecosystems.
This one, which covers the options to reduce emissions to avoid the worst impacts, doesn't offer up brand-new evidence. Instead, like the first two reports, it represents global scientific and even political consensus. Every single sentence of the 63-page summary for policymakers was signed off by representatives of world governments over the past two weeks and haggling over the wording meant its release was delayed by five hours.
New Zealand climate scientist and climate change commissioner Andy Reisinger was the vice chair of the working group that produced the report. He told RNZ the report shows immediate action is needed to keep the most ambitious climate goals alive.
"In terms of urgency, we are pretty much out of time if we want to limit warming to 1.5 degrees, which is what countries agreed to in Paris."
The message is clear: The most catastrophic outcomes can still be avoided, but it will require ambitious action now. The future is still in our hands.
Global inaction
In 1992, the global community pledged to reduce greenhouse gas emissions and stave off climate change. Instead, countries went on to emit nearly as much CO2 in the three decades after the Earth Summit as in the 140 years preceding it.
The IPCC estimated that 58 percent of CO2 emissions since 1850 occurred prior to 1990 and that a whopping 42 percent have happened since. The 2010s saw higher average annual emissions than any other decade on record. Global carbon dioxide emissions averaged 56 billion tonnes between 2010 and 2019 - up by nearly 10 billion tonnes from the previous decade. This was "the highest increase in average decadal emissions on record".
Growth in emissions did slow during the 2010s. Global emissions rose an average of 1.3 percent a year, compared to 2.1 percent between 2000 and 2009.
The third report echoed the conclusions of the first in finding that humanity can afford to emit just 500 billion tonnes of CO2 before we lose even a 50 percent chance of limiting warming to 1.5 degrees. That's less than nine years of emitting at 2019 levels.
Climate policies in place by the end of 2020 were assessed as likely to exhaust that remaining carbon budget in the next decade. Government pledges, which wouldn't be achieved by current policies, are also likely insufficient. The only compatible 1.5 degree pathways would see temperatures briefly reach 1.65 to 1.8 degrees before falling back below 1.5 by 2100. They would also involve massive amounts of net negative CO2 emissions during the second half of the century and require "a rapid acceleration of other mitigation efforts across all sectors after 2030".
Even stopping warming at 2 degrees would be difficult under government pledges. Pathways consistent with both the pledges and warming peaking at 2 degrees "imply annual average global GHG emissions reduction rates of 0-0.7 [billion tonnes of CO2 equivalent] per year during the decade 2030, with an unprecedented acceleration to 1.4-2.0 [billion tonnes] per year during 2030-2050".
The IPCC's evaluation included only those new climate targets announced prior to October 12, 2021. They excluded New Zealand's updated Paris target and those of 24 others which came after the cut-off date.
Equitable cuts
Much of the action will have to come from the richest countries. The IPCC report put the spotlight on inequity across countries and income levels. The poorest and most vulnerable to the impacts of climate change are also generally the least likely to have contributed to the problem.
Two in five people worldwide live in a country with annual emissions of less than 3 tonnes of greenhouse gases per person. That compares with just a third of people living in countries with per capita emissions of more than 9 tonnes a year. In New Zealand, that figure is 17 tonnes.
"Globally, the 10 percent of households with the highest per capita emissions contribute 34-45 percent of global consumption-based household GHG emissions, while the middle 40 percent contribute 40-53 percent and the bottom 50 percent contribute 13-15 percent," the IPCC found.
In 2019, the least developed countries contributed 3.3 percent of global gross emissions and small island developing states emitted 0.6 percent of the world's total. They also bear even less historical responsibility, with least developed countries contributing less than 0.4 percent of cumulative CO2 from fossil fuel burning and industry since 1850 and small island developing states contributing 0.5 percent.
Fossil fuel use can't continue as scheduled to meet any of the more ambitious temperature goals. CO2 emissions from only the currently existing and currently planned fossil fuel infrastructure would blow the world's 1.5 degree carbon budget of 500 billion tonnes. Existing infrastructure is expected to emit a cumulative 660 billion tonnes of CO2 and planned projects would add another 190 billion tonnes to that.
Global fossil fuel use will have to crater in order to limit warming to 1.5 degrees. Coal, oil and gas use in 2050 would have to fall by 95, 60 and 45 percent from 2019 levels, respectively.
Much of the remaining fossil fuel use would involve carbon capture and storage (CCS) technology, in which the CO2 from burning fossil fuels is buried deep underground rather than released to the atmosphere. A 1.5-consistent pathway would see no unabated coal use in 2050 and the burning of oil and gas without CCS falling by 60 and 70 percent from 2019 levels, respectively.
"In these global modelled pathways, in 2050 almost all electricity is supplied from zero or low-carbon sources, such as renewables or fossil fuels with CCS, combined with increased electrification of energy demand," the IPCC reported.
It can be done
Despite the doom and gloom about historic emissions trends and the scale of the challenge facing humanity, the IPCC report is clear that we can still cost-effectively and equitably reduce emissions.
Already, individual and government actions have made progress. Climate policies have "led to the avoidance of emissions that would otherwise have occurred and increased investment in low-GHG technologies and infrastructure," the IPCC said.
"In many countries, policies have enhanced energy efficiency, reduced rates of deforestation and accelerated technology deployment, leading to avoided and in some cases reduced or removed emissions."
Economic and regulatory instruments have reduced emissions by 1.8 billion tonnes a year and laws and executive orders meant that emissions in 2016 were 5.9 billion tonnes below what they would otherwise have been.
In other words, we can make a difference.
Clean energy technologies are now in many cases cheaper to deploy than burning fossil fuels. The levelised costs of energy from solar panels has fallen 85 percent since 2010. Wind energy is 55 percent less expensive. Lithium-ion batteries have seen an 85 percent decline in cost as well.
More than 10 times more electricity is coming from solar now than in 2010. Power from onshore wind has tripled in the same period and offshore wind has also increased by a factor of 10.
The use of large-scale carbon dioxide removal schemes - which could range from planting trees to enabling the ocean to suck up more carbon through chemical process to mechanical solutions which scrub carbon dioxide from the atmosphere and store it underground in geological formations - is "unavoidable" if the world wants to achieve net zero emissions.
But those will have to be complemented by reductions in emissions as well. A range of affordable options are still available.
By 2030, emissions could be cut by a quarter from 2019 levels solely through options that cost less than US$20 per tonne. These come "from solar and wind energy, energy efficiency improvements, reduced conversion of natural ecosystems, and [methane] emissions reductions (coal mining, oil and gas, waste)". Global emissions could be halved by 2030 only through measures costing less than US$100 per tonne.
Models found emissions cuts have a modest impact on global GDP growth - and most of these didn't take into account the cost of inaction. Those that did found "the global cost of limiting warming to 2°C over the 21st Century is lower than the global economic benefits of reducing warming, unless: i) climate damages are towards the low end of the range; or, ii) future damages are discounted at high rates. Modelled pathways with a peak in global emissions between now and 2025 at the latest, compared to modelled pathways with a later peak in global emissions, entail more rapid near-term transitions and higher up-front investments, but bring long-term gains for the economy, as well as earlier benefits of avoided climate change impacts."
Either way, the disastrous consequences of not reducing emissions remain clear, the IPCC said.
"Human-induced climate change is a consequence of more than a century of net GHG emissions from unsustainable energy use, land use and land use change, lifestyle and patterns of consumption and production," it reported. "Without urgent, effective and equitable mitigation actions, climate change increasingly threatens the health and livelihoods of people around the globe, ecosystem health and biodiversity."
