Why Staying Below 1.5°C Is So Important

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In 2018, the United Nations published a special report on the impacts of global warming of 1.5°C and above. As global warming continues to accelerate, it is important to revisit the UN special report and answer why it is crucial to stay below 1.5°C global warming target.

Let me put things into perspective by comparing the earth’s ecosystem with the human body. The normal body temperature for an adult is about 37°C. When our temperature increases by 1°C, we start to feel hot, thirsty and uncomfortable. When the body temperature increases by 2°C, we will experience severe sweating, fast heart rate, exhaustion and pains, which may trigger other health issues. When our temperature increases by 3°C and above, we will get into life-threatening conditions and suffer irreversible damages.

The Problems

Over the past few decades, the global population doubled, rising unevenly. Many countries experienced unprecedented economic growth without putting too much thought into climate change. As a result, the world’s temperature is about 1°C above the pre-industrial times. If we continue to emit at the current level, scientists predict global temperature will pass the 1.5°C mark by 2030. Countries, organizations, and individuals must take immediate and aggressive action to slow down global warming. These actions include both emissions reduction and carbon removal from the atmosphere.


First, global warming has caused extreme and unforeseen weather conditions, such as record-high temperatures, droughts, hurricanes, flooding, and wildfire, and will negatively impact a large population. When the temperature rises another 0.5°C to 1°C, environmental and economic impacts will become more severe. For example, when the world temperature rises by 2°C, the sea level is expected to rise by an extra 10cm, causing devastating effects on over 10 million coastal inhabitants, such as flooding or saltwater entering farmland or contaminating drinking water supplies. The temperature will also accelerate ice sheets melting in Greenland and Antarctica. New research shows Arctic summer sea ice could disappear by as early as 2035. Environmental changes will reinforce the impact of global warming. When the temperature increases by 2°C rather than 1.5°C, an additional 1.5 to 2.5 million square kilometres, the size of Algeria or Mexico, of permafrost will thaw. The process will release a powerful greenhouse gas – methane into the atmosphere, contributing to further warming in a reinforcing feedback loop.

Biodiversity & Agriculture

Second, global warming has also threatened biodiversity and agriculture. When the global temperature rises by 1.5°C – 2.0°C, the loss of biodiversity will double – 18% of insects, 16% of plants, and 8% of vertebrates. All coral reefs will be wiped out at 2.0°C level. Crops, livestock, and fisheries will suffer both quality and quantity, which will add pressure to economic growth and potentially exacerbate tensions among trading partners. The negative impacts on farming and fishing are going to be significant, particularly in the Arctic, drylands, islands, and the poorest countries. However, if we were to achieve the target of keeping global warming to 1.5°C, we would reduce the population susceptible to poverty and climate-related risks by several hundred million by 2050.

Public Health

Third, global warming will continue to intensify serious public health issues and increase the spread of deadly diseases. An additional 0.5°C of warming will enable mosquitoes to carry diseases like malaria and dengue farther and wider. Also, the physical heat will make a whole range of conditions deadlier. It is estimated approximately 300 to 600 million people suffer from malaria annually. Over one million people die from malaria each year, mostly children under five years of age. Our inaction to address global warming issues will greatly impact all human beings over time.

Considering all the negative impacts, do we still think it is too expensive to move toward a low carbon economy? Now, let’s discuss what do we need to do to achieve the 1.5°C degree target.

The Solution

First and foremost, CO₂ emissions must decline by around 45% by 2030 and reach net-zero by 2050. Specifically, methane (the main constituent in Natural Gas) and black carbon (incomplete combustion of fossil fuels, wood, and other fuels) consumption must be reduced by 35% by 2050. Needless to say, these are ambitious targets. In comparison, for the 2°C target, CO₂ emissions must decline by around 20% by 2030 and reach net-zero by 2075. Scientific studies indicate that the permissible carbon emission budget for staying at the 1.5°C degree is between 420 Gt and 570 Gt collectively. Currently, our emission is approximately 42 Gt per year. If we keep the current pace, we will use up all quota in ten to 13 years. This alarming number has not considered how the climate will react to the current levels of global warming and additional emissions from permafrost thawing and methane emitted from wetlands. We don’t know the answers at this point.

Gov. Responsibility

Governments can and should promote more aggressive carbon reduction goals internationally and domestically. The Paris Agreement is a legally binding international treaty on climate change, aiming to reduce annual CO₂ emissions to a level between 52 Gt and 58 Gt per year in 2030. However, in reality, achieving the 1.5°C level target requires greenhouse gas emissions to fall below 35Gt per year by 2030. Governments need to be careful when drafting carbon emission reduction policies as they may have unintended negative impacts. For example, a regulation that promotes using bioenergy to replace fossil fuels can push up nitrous oxide (N₂O), a greenhouse gas, pollution from agriculture. N₂O is 265 times more effective at trapping heat in the atmosphere than CO₂ and depletes the ozone layer. This policy would also raise issues regarding the demand for pasture and arable land.

Major Polluters

However, the most radical changes must come from the big polluting industries. The energy sector needs to ensure 70% to 85% of its power generation is from renewable sources by 2050. Energy-intensive industries must slash their CO₂ by 75% to 90% by 2050. Both the building industry and the transport industry need to ensure 55% to 75% of the total energy supply is from renewable sources by 2050. These goals are not impossible to achieve with existing and new technologies that are technically proven but yet to be deployed or adopted on a larger scale. Costs and constraints associated with the technologies are major hurdles. NUS Consulting Group holds the view that costs and limitations are only temporary challenges to businesses’ existing operations and should not stop companies from transforming to a more sustainable model. We have noticed early movers, usually large multinational companies, are reaping significant rewards for taking a net-zero journey. For example, both Google and Apple have achieved 100% renewable energy supply for its global facilities.

Is it possible to achieve the 1.5°C degree target by merely focusing on carbon removal measures? The answer is more likely to be no. The cost to mitigate energy emissions is tremendous. Recent data shows it would require around $900 billion per year up to 2050 to alleviate energy emissions for the 1.5°C degree target. Also, it is unclear whether carbon removal measures and technologies will remove carbon permanently from the atmosphere at a global scale and potential impacts on land, energy, water, and nutrients. Moreover, the damages caused by global warming are not reversible. Therefore, we believe that carbon removal measures should be used as a supplementary tool rather than the primary mechanism.

How We Can Help

NUS Consulting Group is experienced in helping clients develop and implement a detailed and actionable sustainability plan to reduce their direct and indirect carbon emissions. We periodically produce industry-leading research papers and webinars on sustainability topics. Watch our recent webinar, “Your Net-Zero Journey” and learn more about the sustainability landscape and best practices. Our team leverages energy data intelligence to effectively improve existing procurement and energy management processes and achieve progressive sustainability milestones and targets. Specifically, our procurement services support the purchase of various carbon instruments, green energy, PPAs, and VPPAs. Please contact us for more information.

More: Research Notes, Global Warming, Sustainability

Kevin Tarr-Graham