The science and evidence behind the Positive Power Plan
Your quick guide to climate change
Global warming is no longer a prediction. It is happening now and 2023 is likely to be the hottest year in 100,000 years. In fact, four months in 2023 have already been at least 1.5˚C warmer than pre-industrial times – before humans started burning fossil fuels. On November 17th 2023, the planet officially passed 2˚C global average temperature increase for the first time in recorded history, according to data from Copernicus.
Climate change is the biggest health threat facing humanity, according to a recent major study published in the Lancet – around 40 million people die every year due to climate sensitive diseases, equivalent to 70% of total deaths. It is the responsibility now of all leaders – business, political and social – to drive the rapid replacement of fossil fuels with green energy.
How does climate change work?
Greenhouse gases like carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) trap heat from the sun, creating a “greenhouse effect” that warms the planet. Fossil fuels – coal, oil, and natural gas – release huge amounts of CO2 and other greenhouse gases into the atmosphere when they are burned to make our energy. The excessive release of these gases disrupts the natural balance and leads to significant intensification of the greenhouse effect and global warming.
While some argue that we can continue to burn fossil fuels and bury the resulting emissions underground – a method called Carbon Capture and Storage – the technology is unproven, expensive and has failed multiple times at large scale.
As a global community it’s time to face the reality that the planet is warming up quickly. Without immediate action to transition to green energy, large areas of our planet could become uninhabitable at current rates of fossil fuel usage.
What is currently happening?
Accelerating global warming caused by fossil fuels is already disrupting weather patterns, driving more severe, intense and frequent rainfall, flooding and heatwaves, according to the Intergovernmental Panel on Climate Change (IPCC). Another currently observable pattern is the accelerating rise in air humidity, that when combined with higher temperatures can be lethal.
Fossil fuel emissions not only directly contribute to global warming and changing weather patterns but also trigger feedback loops that amplify the problem. For example, as ice melts due to higher temperatures, there is less ice to reflect sunlight and heat back out into the atmosphere, which further drives global warming.
What’s worse, is that once we pass certain points, we can’t reverse this trend. This is called a “tipping point,” similar to how a seesaw works. Tipping points are triggered at certain levels of warming and include the drying out of the Amazon rainforest and loss of the Great Barrier Reef and other coral reefs. Most tipping points are not only possible, but likely under current warming trajectories.
What is Lethal Humidity?
In 2023, the Intergovernmental Panel on Climate Change (IPCC) confirmed that one of the greatest hazards posed by near-term 1.5°C warming is the impact of “dangerous” humid heatwaves on human mortality. This means that of all the dangerous impacts of the climate crisis, humid heatwaves is one of the nearest dangers we face according to major scientific consensus.
According to The National Aeronautics and Space Administration (NASA), for every degree the planet warms, humidity rises 7%. On this basis, it is likely that humidity has risen roughly 10% since the 1850s. Increasing temperatures combined with high humidity can be lethal for humans. As our oceans warm from rising temperatures, more water evaporates, further increasing humidity in the air. This drives energy into the atmosphere and stirs up violent and frequent weather events like storms and hurricanes.
We are all at extreme risk from the combined threat of lethal heat and humidity. In response to this evidence, Fortescue has formed a Lethal Humidity Global Council. This is a group of scientists from a range of world leading universities, including:
Oxford University, Cambridge University, Delft University of Technology, Harvard University, Massachusetts Institute of Technology (MIT), Brookings Institution, University of California Los Angeles (UCLA), University of California Santa Barbara (UCSB), University of California Berkely, Stanford University, the Australian National University (ANU), the University of Melbourne, the University of Sydney, the University of Monash, the University of Western Australia (UWA), Central South University, Tsinghua University, Peking University, Shanghai Jiao Tong University, Indian Institute Of Technology (IIT) in Delhi, Chennai and Mumbai, the Federal University of Ceará, the University of Brazil and Roma Tre University.
These scientists collectively warn that Lethal Humidity, if left unchecked, will be responsible for mass deaths and migration in parts of the world, particularly the tropics and the sub-tropics.
What are scientists saying about Lethal Humidity?
“The lethal combination of high temperature and high humidity, due to the climate crisis, could kill many people. This is a race against time to save ourselves. We must go all out.” - Professor Li Zheng, Institute of Climate Change and Sustainable Development, Tsinghua University
“Humidity aggravates the killing power of heat. It can trigger catastrophic events like heart attacks and stroke. It’s a silent killer.” Professor Ambarish Dutta, Professor of Epidemiology, IIPH Bhubaneswar
“There is an upper limit to human survival – and fossil fuels are pushing us closer to that limit. At temperatures of around 30C upwards, combined with high humidity, we can’t cool ourselves by sweating and death can result. Already, many parts of the world are at risk. Policy makers and business leaders must show leadership and accelerate action on the climate crisis.” - Dr Shanta Barley, Chief Climate Scientist at Fortescue
“Unless the world acts swiftly, large parts of the world could experience significant periods when it is so hot and humid that it is potentially fatal to venture outside.” - Professor Nick Stern, London School of Economics.
What’s the difference between dry heatwaves and humid heatwaves and how will they be affected by global warming?
Dry heatwaves involve clear skies and intense heat, whereas humid heatwaves tend to be characterized by oppressive, humid conditions both during the day and night.
While many parts of the world will become even hotter and more humid as water vapor in the atmosphere rises, some regions will dry out, inflicting harm on humans in other ways.
Ha et al (2022) Dynamics and characteristics of dry and moist heatwaves over East Asia. NPJ Climate and Atmospheric Science
Sydney Morning Herald
Raymond et al (2020) The emergence of heat and humidity too severe for human tolerance. Science Advances DOI: 10.1126/sciadv.aaw1838.
Song et al (2022). Trends in surface-equivalent potential temperature: A more comprehensive metric for global warming and weather extremes. PNAS. 119: 6, e2117832119
Sherwood et al (2010) An adaptability limit to climate change due to heat stress. PNAS, 107: 21, 9552-9555
IPCC Synthesis Report 2023
Beggs and Zhang (2023) The Lancet Countdown on health and climate change: Australia a world leader in neglecting its responsibilities. Med J Aust doi: 10.5694/mja2.52152
Chen et al (2022) Increases of extreme heat-humidity days endanger future populations living in China. Environmental Research Letters. 17: 064013
Copernicus analysis: 2°C warming in November 2023
Dawei Li et al (2020). Escalating global exposure to compound heat-humidity extremes with warming. Environ. Res. Lett. 15: 064003
Douville et al (2022) Global warming at near-constant tropospheric relative humidity is supported by observations. Nature Communications, Earth & Environment. 3:237
Huang et al (2023) Humidity may amplify the temperature-related health risks in the context of climate change. Europe PMC
Freychet et al (2022) Robust increase in population exposure to heat stress with increasing global warming. Environ. Res. Lett. 17 064049. DOI: 10.1088/1748-9326/ac71b9
Im et al (2017) Deadly heat waves projected in the densely populated agricultural regions of South Asia. Science Advances 3:8 DOI: 10.1126/sciadv.1603322
Kang and Eltahir (2018) North China Plain threatened by deadly heatwaves due to climate change and irrigation. Nature Communications 9: 2894
Liu et al (2018) Projected Changes in Extreme High Temperature and Heat Stress in China. J. Meteor. Res., 32(3): 351-366. DOI: 10.1007/s13351-018-7120-z
McKay et al (2022) Exceeding 1.5°C global warming could trigger multiple climate tipping points
Saeed et al (2021) Deadly heat stress to become commonplace across South Asia already at 1.5C global warming. Geophysical Research Letters. 48:7
Raymond and Horton (2017) Spatiotemporal Patterns and Synoptics of Extreme Wet-Bulb Temperature in the Contiguous United States. Journal of Geophysical Sciences: Atmospheres. 122: 13108–13124.
Russo et al (2017) Humid heat waves at different warming levels. Scientific Reports. 7: 7477
Speizer et al (2022) Concentrated and Intensifying Humid Heat Extremes in the IPCC AR6 Regions. Geophysical Research Letters 49:5 e2021GL097261
Vecellio et al (2022) Evaluating the 35C wet-bulb temperature adaptability for young health subjects. J Appl Physiol DOI: 10.1152/japplphysiol.00738.2021
Vecellio et al (2023) Greatly enhanced risk to humans as a consequence of empirically determined lower moist heat stress tolerance. PNAS 120 (42) e2305427120
Wang et al (2020) Intensified humid heat events under global warming. Geophysical Research Letters 48:2
Zhang et al (2021) Projections of tropical heat stress constrained by atmospheric dynamics. Nature Geoscience, 14:3
Zhang et al (2023) Increased heat risk in wet climate induced by urban humid heat. Nature 617: 738-742