THE AIR

OUR HOUSE IS ON FIRE

Over 50% of the human addition of carbon to the atmosphere through the burning of fossil fuels has occurred in the last 25 years — i.e., since the IPCC was founded.

Human activities have caused the planet’s average surface temperature to rise about 1.1°C since the late 19th century. Most of the warming has occurred in the past 35 years.

Globally, the past four years have been the hottest on record, and the 20 warmest have occurred in the past 22 years. https://public.wmo.int/en/files/gmtprepng

As the global temperatures rises, we see an increase in extreme weather events such as heat waves and droughts. For example, scientists from the UK Met Office examined the extreme heat wave that struck Europe in the summer of 2003 (now known to have killed 70,000 people) and concluded that “it is very likely…that human influence has at least doubled the risk of a heat wave exceeding this threshold magnitude.”  If we carry on burning fossil fuels, such an extreme heat wave will become an average summer for Europe by 2040, and almost all summers will be hotter than that by 2060! As shown in this graph:

Across the globe, calculations show that record-breaking extreme temperatures have become far more probable due to human-induced warming (for example: 2010 Syria;  2013 Korea; 2014 California; 2018 UK).

A 2018 study shows how deadly heat waves may limit the habitability of one of the world’s most populous regions. It concluded that continued burning of fossil fuels would lead to heat extremes that exceeded “the threshold defining what Chinese farmers may tolerate while working outdoors.”

Climate change is here in your lifetime:

MASS EXTINCTION

A “biological annihilation” of wildlife in recent decades means the Sixth Mass Extinction in Earth’s history is underway.

Looking at the U.S., for example, a 2018 report by the National Wildlife Federation, the American Fisheries Society, and the Wildlife Society found that one of every three wildlife species in the country is vulnerable to extinction. 650 U.S. species are either known to be extinct already or have not been sighted at all in recent decades. The species affected include important pollinators like monarch butterflies, whose population in California declined by 86 percent in 2017-2018 alone. 70% of the U.S.’s freshwater mussels, which uphold food chains and water quality in river systems, are also imperiled or extinct. The same was already true of one in six American mammals and one in seven birds more than 20 years ago, according to the Nature Conservancy.

Globally, species are going extinct at rates up to 1,000 times the background rates typical of Earth’s past. The direct causes of biodiversity loss are habitat change, overexploitation, the introduction of invasive alien species, nutrient loading, and climate change.

The average rate of vertebrate species loss over the last century is up to 100 times higher than the background rate. The total number of vertebrate species that went extinct in the last century would have taken about 800 to 10,000 years to disappear if the background rate had prevailed.

The latest Living Planet Index shows an average decline of 60% in population sizes of thousands of vertebrate species around the world between 1970 and 2014.

More than a quarter of the assessed species (around 100,000) are threatened with extinction. That is 40% of all amphibians, 25% of all mammals, 34% of all conifers, 14% of all birds, 33% of reef-building corals, and 31% of sharks and rays.

Corals reefs are suffering mass die-offs from heat stress.  These events are becoming much more common with back to back die-offs on the Great Barrier Reef in Australia in 2016 and 2017. The predictions are that at even at 2C of warming these heat waves will occur on an annual basis.

“20 years from now, every summer will be too hot for corals: they will disappear as dominant members of tropical reef systems by 2040-2050. It’s hard to argue it any other way.” – Prof. Ove Hoegh-Guldberg, director of the Global Change Institute at the University of Queensland.

INSECT DIE-OFF

Catastrophic reductions in global insect populations have profound consequences for ecological food chains and human crop pollination.

There is strong evidence that many insect populations are under serious threat and are declining in many places across the globe. Multiple pressures might include habitat loss, agro-chemical pollutants, invasive species, and climate change.

A 27-year-long population monitoring study in Germany revealed a dramatic 76% decline in flying insect biomass.

And a new study by Dutch scientists found that butterfly numbers had fallen by over 80% in the last 130 years. The authors concluded that “industrial agriculture is simply leaving hardly any room for nature.”

FOOD

One of the world’s leading medical journals, The Lancet, carried out a major review which concluded that climate changed posed “the biggest global health threat of the 21st century” because of both the direct impacts of extreme weather events and indirect disruption to the social and ecological systems that sustain us.

Food insecurity

More frequent and severe water extremes, including droughts and floods, impact agricultural production, while rising temperatures translate into increased water demand in agriculture sectors.

“We have already observed impacts of climate change on agriculture. We have assessed the amount of climate change we can adapt to. There’s a lot we can’t adapt to even at 2ºC. At 4ºC the impacts are very high and we cannot adapt to them” – Dr. Rachel Warren, University of East Anglia

The number of extreme climate-related disasters, including extreme heat, droughts, floods, and storms, has doubled since the early 1990s, with an average of 213 of these events occurring every year during the period of 1990–2016. These harm agricultural productivity, contributing to shortfalls in food availability, with knock-on effects causing food price hikes and income losses that reduce people’s access to food.

People across 51 countries and territories face crisis levels of acute food insecurity or worse, requiring immediate emergency action.

• 2015: 80 million people

• 2016: 108 million people

• 2017: 124 million people

The risk of extreme weather hitting several major food-producing regions of the world at the same time could triple by 2040 (1-in-100-year event to 1-in-30).

A recent study looking at the impact of climate change on food production for the top four maize-exporting countries, which currently account for over 85% of global maize exports, found that “the probability that they have simultaneous production losses greater than 10% in any given year is presently virtually zero, but it increases to 7% under 2°C warming and 86% under 4°C warming.”

WATER

DROUGHT AND SCARCITY

Water withdrawals grew at almost twice the rate of population in the twentieth century.

The global water cycle is intensifying due to climate change, with wetter regions generally becoming wetter and drier regions becoming even drier. A 2018 UN report highlights that at present, an estimated 3.6 billion people (nearly half the global population) live in areas that are potentially water-scarce at least one month per year, and this population could increase to some 4.8–5.7 billion by 2050.

Rising temperatures will melt at least one-third of the Himalayas’ glaciers by the end of the century even if we limit the temperature rise to 1.5°C. Melting glaciers in both the Andes and the Himalayas threatens the water supplies of hundreds of millions people living downstream.

A severe drought in Cape Town in 2018 led to severe water restrictions being put in place. The city came to within just days of turning off its water supply – dubbed ‘Day Zero’. Climate scientists have now calculated that climate change has already made a drought of this severity go from a 1-in-300-year event to being a 1-in-100 year event. At 2°C of warming, a drought of this severity will happen roughly once every 33 years.

RISING SEAS

Sea level rises have accelerated in recent decades. Rising sea levels are caused primarily by two factors related to global warming: the added water from melting ice sheets and glaciers and the expansion of seawater as it warms. Sea level rises will cause inundation of low-lying land, islands, and coastal cities globally.

As the sea level rises higher over the next 15 to 30 years, tidal flooding is expected to occur much more often, causing severe disruption to coastal communities and even rendering some areas unusable — all within the timeframe of a typical home mortgage.

2°C warming would threaten to inundate areas now occupied by 130 million people while an increase to 4°C could lock in enough eventual sea level rise to submerge land currently home to 470 to 760 million people globally.

The land ice sheets in both Antarctica and Greenland have been losing mass since 2002. Both ice sheets have seen an acceleration of ice mass loss since 2009. Antarctica is losing six times more ice mass annually now than it was 40 years ago.

In 2014, a team from NASA found that part of the West Antarctic ice sheet had already begun what they described as an “unstoppable” collapse, locking in at least a meter of sea level rise. If we continue warming, we will trigger the collapse of more sectors of the ice sheets.

“Sea level is rising much faster and Arctic sea ice cover shrinking more rapidly than we previously expected. Unfortunately, the data now show us that we have underestimated the climate crisis in the past.” Stefan Rahmstorf, Professor of Physics of the the Oceans.