Forecasting Climate Deaths

Nigel Howard collaborated with Professor Newman (Curtin) in a 4 year long project to estimate the lives lost due to climate change and to forecast the lives likely to be lost due to our historic and continuing emissions.  Their paper on Forecasting Lives Lost to Climate Change is published to the EarthArXiv Preprint server here DOI: https://doi.org/10.31223/X5TJ58. 

The findings are shocking and controversial for the scale of climate deaths and for the rate at which deaths will accumulate and decimate human population.  Currently there are probably 10m climate deaths per year (mostly children in Africa from undernourishment).  Our current trajectory (BAU) forecasts undernourishment spreading globally and deaths rising to over 70m in the 2050’s and population decline from over 8bn to 4bn by 2300. Most of this can be mitigated if we get really serious globally about radical decarbonisation to zero as soon as possible.  Although the findings are subject to large uncertainty mankind cannot afford to ignore them from a precautionary standpoint.  If we are wrong then the only consequence is a global transition to marginally free renewable energy before we needed to – if we are right the consequences for human population and a survivable future are dire.  This work is a starting point and needs to be continuously refined as more and better data and modelling becomes available.  Meanwhile whole nations, governments, corporations and investors need to be acting on this precautionary science NOW and our youth need to be advocating and challenging our institutions, governments and corporations in court for the intergenerational  implications of this work.

 This work established a model of:

• CO₂ emissions correlated with the UN 2024 population growth forecasts
• incorporating scenarios for emissions reduction from 2030 to 2050 (Paris commitments), by 2060, by 2070 and continuing on the current BAU emissions trends
• global atmospheric CO₂ concentration based on emissions net of natural drawdown (CO₂ dissolving in oceans, photosynthetic, alkaline mineral weathering)
• global mean surface temperatures (GMST) correlated with global atmospheric CO₂ concentrations
• Undernourishment and Conflict are considered inextricably linked in the literature, so are modelled together.  Undernourishment deaths are assumed at 1.2% (WFP Director) of those undernourished and combined with conflict deaths. 
• For 20 different regions, the combined starvation and conflict deaths data are iteratively separated into the reducing trend of deaths with time (development/prosperity) from the increasing trend with global atmospheric CO₂ concentrations. 
• For some regions, either their agriculture is not yet significantly climate affected or their populations are wealthy enough to afford imported food, masking climate vulnerability.  For these regions latitude is used to extrapolate likely climate vulnerability. 
• Economic growth and the distribution of incomes in each region are correlated with undernourishment to determine an income threshold below which people must rely on domestic food production and above which people can afford imported food to meet any shortfall in agricultural productivity.  The proportion of population suffering undernourishment and climate deaths is taken as the minimum of the proportion climate exposed and the proportion economically exposed multiplied by regional population.
• The sum of undernourishment and conflict deaths for each region provides the estimated global forecast of undernourishment and climate deaths. 
• Disaster numbers, from the EMDAT disaster database (compiled since 1900) were correlated with global atmospheric CO₂ concentrations for:
• Drought
• Wildfire
• Storm
• Flood
• Mass Movement wet and dry
• Epidemic

[Earthquake, Volcanic activity and Drought were excluded due to lack of population normalised correlation]

• Climate caused disaster deaths were estimated as the product of disaster numbers and average deaths per disaster from the EMDAT disaster database
• Air Pollution deaths were forecast at 20,000 per DegC of warming (Jacobson, 2008)
• Review of other available health related climate impacts revealed either lack of consensus between studies or lack of apparent climate correlation.  Of 756 climate mortality causes in the WHO database, only 88 showed even a tentative increase with CO2 emissions, whilst 160 showed a decrease, hinting that overall climate change may reduce health deaths, but much more work is needed)
• Summing deaths per year
• Extrapolating all trends forward for all scenarios to 2300 and compiling cumulative deaths and cumulative emissions
• Determining the cumulative deaths per cumulative emissions ratio for each scenario and the 95% confidence limits on all of the forecasts.

There are some significant assumptions made in this modelling (detailed in the report) and large inherent variability and uncertainty in the results.  It is envisaged that this modelling will be updated and refined periodically as climate change worsens and more data arises.  This will improve confidence in the modelling and narrow the confidence limits.

These deaths will most be caused by starvation and conflict:

Clarity Environment can provide advice on the climate deaths attributable to any product, service, investment or government or corporate policy for which the carbon or CO₂-e emissions can be estimated.  We will provide this advice pro-bono to environmental advocacy organisations attempting to hold governments, corporations or investors to account for their true climate liabilities.