Explained: The crucial 1.5 degrees Celsius climate target and IPCC’s “now or never” warning

In its latest report, the Intergovernmental Panel on Climate Change (IPCC) said if the world wanted to restrict temperature rise to within 1.5 degree Celsius then global greenhouse emissions needed to peak by 2025 “at the latest”

The fight to keep global warming under 1.5 degrees Celsius has reached the “now or never” phase, warns a new report released Monday by the world’s leading climate scientists. Global emissions can be halved by 2030 with major transitions in the energy sector, including a substantial reduction in fossil fuel use, said The Intergovernmental Panel on Climate Change (IPCC), a United Nations body that assesses the science related to climate change.

The IPCC Working Group III report “Climate Change 2022: Mitigation of Climate Change”, said that without immediate deep emissions reduction across all sectors, limiting global warming to 1.5 degrees Celsius is beyond reach.

What is the 1.5 degrees Celsius limit that the report refers to? And why is it crucial?

The need to limit global warming to 1.5 degrees Celsius is always emphasised in climate reports and summits.

The 2015 Paris Agreement, a legally binding international treaty on climate change, commits countries to limit the global average temperature rise to well below 2?C above pre-industrial levels, and to aim for 1.5?C.

Climate leaders and scientists have warned that crossing the 1.5?C threshold risks unleashing far more severe climate change effects on people, wildlife, and ecosystems.

Warning that the world is on a “fast track” to disaster, UN Secretary-General Antonio Guterres said, “It is time to stop burning our planet…”

What is the earth’s temperature now?

Earth’s global surface temperature has increased by around 1.1 ?C compared with the average compared between 1850 and 1900. Each of the last four decades has been hotter than any decade since 1850. Such a rise in temperatures hasn’t been witnessed since 125,000 years ago, before the most recent ice age.

How will the 1.5 degrees Celsius be measured?

The declaration that Earth has reached 1.5? warming since the pre-industrial era will not be made after a single year, or a single location, passes that threshold, reports The Conversation.

The warming is measured as a global average over 20 years, to account for natural variability in the system.

Before global average temperatures officially reach 1.5? warming, we can expect quite a few years will exceed that limit. Global temperatures exceeded 1.5? warming during individual months at the peak of the 2015-16 El Nino, the report says.

Heat waves are becoming more severe, as we are already witnessing across India. AFP

What happens if the hotting up continues?

Climate change is affecting every part of the globe. “For every increment of global warming, changes in extremes become larger,” climate scientist Sonia Seneviratne at ETH Zurich told Reuters last year.

Heat waves become more severe, as we are already witnessing across India, and they are now occurring in areas where they did not before. A study published by scientists at the Banaras Hindu University’s Mahamana Centre of Excellence in Climate Change Research found that heat-wave patterns in India have shifted, with a significant increase in heat waves in north-western, central, and south-central India. The country witnessed the hottest March in the last 122 years in 2022.

An extreme heat event that occurred once per decade in a climate without human influence, would happen 4.1 times a decade at 1.5?C of warming, according to the IPCC.

A warmer atmosphere holds more moisture and this results in extreme rainfall, increasing the risks of floods. It also increases evaporation, leading to more intense droughts.

In 2021, torrential rains flooded China and Western Europe, killing hundreds. Hundreds more died when temperatures in the Pacific Northwest hit record highs. Greenland saw massive melting events, wildfires ravaged the Mediterranean and Siberia, and a record drought affected parts of Brazil, Reuters reported.

Can we keep the 1.5 degrees Celsius target?

While some climate experts are positive, others believe that the target is slipping out of reach faster than we can imagine.

“Is it still possible to limit global warming to 1.5 ?C? The answer is yes,” Maisa Rojas, Chile’s environment minister and a lead author of the IPCC report, said last August.”But unless there are immediate, rapid, and large-scale reductions of all greenhouse gases, limiting global warming to 1.5 ?C will be beyond reach.”

After the first part of the IPCC report was released last year, teenage climate activist Greta Thunberg has said that at the current emission rate, the 1.5 degrees Celsius target will be exceeded by 2026.

What needs to be done to meet the goal?

According to Monday’s report, to achieve the 1.5 degrees Celsius target, the world must reduce annual carbon dioxide emissions by 48 per cent by 2030, and reach net zero by 2050, while reducing methane emissions by a third by 2030 and almost halving them by 2050. Global greenhouse emissions needed to peak by 2025 “at the latest” if the world wanted to restrict temperature rise to within 1.5 degree Celsius from pre-industrial times.

“The last two decades saw the highest increase in emissions in human history. Even though we know how much trouble we are in, the next decade cannot follow the same pattern if we are to hold the warming to 1.5 degrees Celsius. Half measures will not half greenhouse gas emissions by 2030. IPCC tells us that we have the knowledge and the technology to get this done,” said Inger Anderson, executive director, United Nations Environment Programme.

Joyashree Roy, one of the coordinating authors of the report, said an important takeaway from the report is that the next few years will be critical when countries will decide on mitigating actions. “Unless mitigation action is taken, 1.5 degrees limit cannot be reached. We need to ramp up action without delay. The report says there are ways to improve our chances of success to limit global warming to 1.5 degrees Celsius,” Roy said while talking to the media.

“Limiting global warming will require major transitions in the energy sector. This will involve a substantial reduction in fossil fuel use, widespread electrification, improved energy efficiency, and use of alternative fuels (such as hydrogen),” the report said.

Each of the last four decades has been hotter than any decade since 1850. AFP

What is being done so far?

“We are at crossroads. The decisions we make now can secure a liveable future. We have the tools and know-how required to limit warming,” said IPCC Chair Hoesung Lee.

“I am encouraged by climate action being taken in many countries. There are policies, regulations, and market instruments that are proving effective. If these are scaled up and applied more widely and equitably, they can support deep emissions reductions and stimulate innovation,” Lee said on Monday.

The United States, European Union, and the United Kingdom are leading the race to cut emissions targets among the world’s biggest economies. The UK has committed to cutting emissions at a faster rate than other developed nations, with a target of 68 per cent cuts by 2030.

What about India?

India is the third-largest emitter of carbon dioxide (CO2) after China and the US. Prime Minister Narendra Modi has set a target of net-zero greenhouse gas emissions by 2070.

The country has also pledged that it will increase its non-fossil fuel energy capacity to 500 gigawatts (GW) by 2030. It currently has a capacity of around 157GW.

With inputs from agencies

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