By Robert A. Vella

Of all the foreseen – and possibly unforeseen – impacts from climate change, including extreme weather, sea level rise, and ecosystem degradation, none poses such an imminent threat to our Earthly human population as does food shortages. The United Nation’s latest projection on world population growth indicates we’re on a pace to reach 11.2 billion in the year 2100. It assumes there will be sufficient food to support those additional 3.9 billion people (the current population is 7.3 billion). But, according to recent projections released by the Intergovernmental Panel on Climate Change (IPCC), it is doubtful whether the longstanding increases in global food production we’ve been accustomed to will continue. In fact, many experts have estimated that worldwide food shortages might begin to be realized as early as 2030 – a mere 15 years from now.

IPCC Crop Yield Projections

IPCC Crop Yield Projections


While the amount of effort being put into these projections is apparent, it is very difficult to find credible, publicly-available studies on the relationship between population growth and food supplies with respect to climatic changes in the 21st century. This information is imperative, in my opinion, if we are to anticipate and mitigate a potential crisis of such great magnitude. Therefore, I will endeavor to do so here.

First, let’s understand the scale of the problem. From The GuardianIPCC report warns of future climate change risks, but is spun by contrarians:

The Intergovernmental Panel on Climate Change has just published its latest Working Group II report detailing impacts, adaptation, and vulnerability associated with climate change. The picture it paints with respect to the consequences of continued climate change is rather bleak.

For example, the report discusses the risk associated with food insecurity due to more intense droughts, floods, and heat waves in a warmer world, especially for poorer countries. This contradicts the claims of climate contrarians like Matt Ridley, who have tried to claim that rising carbon dioxide levels are good for crops.

While rising carbon dioxide levels have led to ‘global greening’ in past decades and improved agricultural technology has increased crop yields, research has indicated that both of these trends are already beginning to reverse. While plants like carbon dioxide, they don’t like heat waves, droughts, and floods. Likewise, economist Richard Tol has argued that farmers can adapt to climate change, but adaptation has its costs and its limits. In fact, the IPCC summary report notes that most studies project a decline in crop yields starting in 2030, even as global food demand continues to rise.


As Chris Field, Co-Chair of Working Group II noted,

“With high levels of warming that result from continued growth in greenhouse gas emissions, risks will be challenging to manage, and even serious, sustained investments in adaptation will face limits”

We’re committed to a certain amount of climate change, and as glaciologist Lonnie Thompson famously put it, “The only question is how much we will mitigate, adapt, and suffer“.

Note the generalized warnings in the article which omit any specific references to population impacts. I do appreciate the scientific, journalistic, and governmental hesitancy towards such specificity. Professional careers could be jeopardized and unnecessary fear-mongering could trigger panic in the public. Although, it’s hard to believe that science and government have not already researched the potential outcomes of major food shortages.

Using the data from the IPCC Crop Yield Projections, I created a spreadsheet to calculate a numerical value representative of the aggregate quantitative mean and qualitative average of all projections within a given range. The resulting “Net Rating” values would be compared against the late-20th century crop yield norm to illustrate how variant each range of projections might be. Here’s my methodology:

IPCC Crop Yield Projections - Net Rating Calculator Snapshot

IPCC Crop Yield Projections – Net Rating Calculator Snapshot


Next, I overlaid these net rating results relative to the late-20th century crop yield norm onto the U.N World Total Population projections graph:

UN World Population Projection versus IPCC Crop Yield Projections

UN World Population Projection versus IPCC Crop Yield Projections


The graph projects global crop yields will peak in 2020, five years from now, and then decline towards the end of the century (with a temporary modest increase around the year 2080). Coincidentally, or not, the net rating projections (purple line) dip below the late-20th century crop yield norm (green line) immediately after 2030 – the year cited by experts as the possible beginning of major food shortages. The net rating projections also appear to parallel the U.N.’s (deterministic) low variant of the (+/-0.5 child) 2015 Revision of the World Population Prospects. That projection limits the apex of world human population to under 9 billion (mid-2050s), and the end of century level to approximately 7 billion.

It should also be noted that few, if any, of the IPCC crop yield projections assume global warming to surpass the 2C threshold set by climate scientists as an upper limit to manageable adaptation. However, at our current and forecasted rate of greenhouse gas emissions, we will blow past that threshold within this century (see: Global-warming limit of 2 °C hangs in the balance). Beyond 2C, the IPCC crop yield projections – distressing as they are – would be overstated.

The focus of this statistical analysis centers on crop yields because agricultural production constitutes the bulk of the world’s food supply (see: Food security). According to the Food and Agriculture Organization of the United Nations (FAO), proteins derived from fish, crustaceans and mollusks only account for 13.8% to 16.5% of the animal protein consumed by the human population (as documented in 2003, see: Global and regional food consumption patterns and trends). Furthermore, wild fisheries have already reached their maximum potential for production and, in the wording of the report, it is “unlikely that substantial increases in total catch will be obtained in the future.” Proceedings of the National Academy of Sciences (PNAS) echoed this assessment in 2007 by stating that “very low confidence can be placed in current predictions of future fish production” (see: Global fish production and climate change). Although aquaculture (farm-raised fish) has been increasing in recent years (see: World fisheries production), it is uncertain how climate change impacts – such as ocean acidification – will affect such production techniques going forward.

In conclusion, it can be asserted that the interaction between projected world population trends and projected global crop yields will likely reduce Earth’s human population growth by at least 4 billion people by the end of this century. From a statistical point of view, this is just an abstract number. From a humanistic point of view, the figure represents an unprecedented catastrophe. For it is the individual mothers, fathers, daughters and sons inhabiting this planet of ours who will suffer the dire consequences of anthropogenic climate change.

Further reading:

Climate Change Seen Posing Risk to Food Supplies

Current global food production trajectory won’t meet 2050 needs

Extreme Weather Putting Food Production at Greater Risk

How to Double Global Food Production by 2050 and Reduce Environmental Damage

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