Difference between 1.5° and 2.0°C warming

This infographic is from the WWF, and I’m just going to leave it here:

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Water-Energy-Food Nexus

The food-energy-water nexus refers to the way that water security, energy security and food security (all vital for human well-being, poverty reduction and sustainable development) are strongly linked to one another, so the actions in any one area often have effects in one or both of the others:

Source: IWA, 2018. Sustainable Development: The Water-Energy-Food Nexus.

Here are some key facts and figures about this nexus from the UN website: https://www.unwater.org/water-facts/water-food-and-energy/

  • While almost 800 million people are currently hungry, by 2050 global food production would need to increase by 50% to feed the more than 9 billion people projected who live on our planet (FAO/IFAD/UNICEF/WFP/WHO, 2017).
  • 72% of all water withdrawals are used by agriculture, 16% by municipalities for households and services, and 12% by industries. (UN-Water 2021)
  • It typically takes between 3,000 and 5,000 litres of water to produce 1 kg of rice, 2,000 litres for 1kg of soya, 900 litres for 1kg of wheat and 500 litres for 1kg of potatoes. (WWF).
  • In sub-Saharan Africa, irrigated areas are expected to more than double by 2050, benefiting millions of small-scale farmers. However, it has been estimated that 41% of current global irrigation water use occurs at the expense of environmental flow requirements. (FAO 2020)
  • The food production and supply chain accounts for about 30% of total global energy consumption. (FAO, 2011)
  • 90% of global power generation is water-intensive. (UN, 2014)
  • Power plant cooling is responsible for 43% of total freshwater withdrawals in Europe (more than 50% in several countries), nearly 50% in the USA, and more than 10% of the national water cap in China. (UN, 2014)
  • Global water demand (in water withdrawals) is projected to increase by 55% by 2050, mainly because of growing demands from manufacturing (400% increase). (OECD, 2012)
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Global greenhouse gas emissions by sector

The Paris Agreement which came into force in 2016 is a legally binding agreement in which almost all nations of the world agreed to put in place policies to keep global climate warming to below 2°C and ideally below 1.5°C above pre-industrial levels. The 2018 IPCC Special Report on Global Warming of 1.5°C, that was commissioned as a result of the Paris meeting concluded that:

The report finds that limiting global warming to 1.5°C would require “rapid and far-reaching” transitions in land, energy, industry, buildings, transport, and cities. Global net human-caused emissions of carbon dioxide would need to fall by about 45 percent from 2010 levels by 2030, reaching ‘net zero’ around 2050. This means that any remaining emissions would need to be balanced by removing CO2 from the air.

This is obviously an incredible challenge. Even a global pandemic and associated ‘shut down’ of some sectors of economic activity only caused a small blip in global emissions, as described in this article.

So what human activities are producing greenhouse gases?

Where can we focus our efforts?

And what about the social justice aspect?

Emissions are currently quite strongly related to GDP, so how can we reduce our emissions while still fulfilling peoples life aspirations?

You can read more about greenhouse gas emissions from Our World in Data here: https://ourworldindata.org/co2-and-other-greenhouse-gas-emissions

And you can look at the emissions over time and the impacts of COVID on the IEA website here: https://www.iea.org/data-and-statistics/charts/global-energy-related-co2-emissions-1900-2020

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World population and its appetite

Astonishing: When I was born we were 4.8 billion strong, and 55% of the land was classified as ‘wilderness’. Today we are about 7.8 billion, and less than 35% of the planet is wilderness. Relatedly, this is what the composition of mammals on earth looks like (curiously displayed by weight thanks to xkcd):

We far outnumber our wild mammal cousins, and a huge weight of mammals is taken up by our lovely big beautiful bovine friends, almost exclusively kept for meat or milk. So what does it take to feed the humans of this world?

You can explore more population and agriculture data from Our World in Data here: https://ourworldindata.org/world-population-growth and here: https://ourworldindata.org/environmental-impacts-of-food


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Common errors in (student) science writing

Ah, the glories of Twitter led me to this marvellous short handout by David Schulz titled “How to improve upon common errors in student science writing“. At only 7 pages long theres little excuse not to read this document and it helps me answer my colleagues questions on scientific english as well. So many small editorial aspects that I was never formally taught.

“For Critical Literature Reviews, dissertations, and other research papers, rather than just mentioning in passing the lack of consensus in the literature or the gap in the literature, motivate it in the introduction by describing how the lack of consensus is affecting the science. If there is a debate, provide enough evidence for and against to motivate your reader. The reader should understand your concerns. Can you provide an example? Can you quantify what the failure to address this issue is doing? Otherwise, readers may not get the sense from what you’ve written what the debate is all about and why they should care.”

David M. Schultz is a Professor of Synoptic Meteorology at the Centre for Atmospheric Science of the University of Manchester, Chief Editor for Monthly Weather Review, and author of “Eloquent Science: A Practical Guide to Becoming a Better Writer, Speaker, and Atmospheric Scientist“. His website http://eloquentscience.com is full of other tips and tricks.


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