The Orchardist

Climate change

- By Elaine Fisher

Planet Earth is on a trajectory towards two possible outcomes – “Stabilised Earth” in which humans could survive, and “Hothouse Earth” where they may not, Will Steffen, Earth System scientist and Emeritus Professor at the Australian National University told delegates at the Zespri Momentum Conference at Mount Maunganui in February.

If the world manages to keep global warming to the Paris Agreement of 1.5 or 2 degrees Celsius, the Earth’s climate will be harsher, some places uninhabita­ble and food production won’t be possible in some regions.

Population levels could drop in some parts of the world, and in some places, people would have to live indoors because of extreme heat and rely on desalinati­on plants for water supply. “There’s a huge amount at stake.”

If warming went up by three to five degrees, that would very likely lead to Hothouse Earth, conditions which could not be reversed.“i think humans could not live in those conditions.this would possibly lead to a collapse of civilisati­on as we know it today,” Will Steffen said.

“We can still cap the climatic changes, but not with business as usual. Up until the last decade we had a chance to control temperatur­e rise at moderate levels, but we are now moving closer to a possible planetary tipping point which would take Earth out of our control.the choice is ours.”

Should “Stabilised Earth” conditions be achieved, that would lead to “a much better social outcome, and a more equitable society. But we would still have to adapt to a harsher climate. We would be able to grow many of the things we grow today, but not always in the same places. There will be big shifts.”

New Zealand could be hit less than others because it is a small landmass in the centre of big oceans, but this country won’t escape unaffected. However, at a 2-degree average increase in temperatur­es, life in Australia would be tough.

Will said that from the middle of last century there were clear trends showing the Earth was getting hotter at an accelerati­ng rate. “This is not natural, and we know exactly why it is happening.”

The increasing temperatur­es correlate well to an increase in human generated greenhouse gas emissions, which

accelerate­d in the 1950s as population­s used more electricit­y, travelled more and consumed more fossil fuels.

“And fundamenta­l physics tells us that increase in greenhouse gas emissions is the primary cause of the temperatur­e rise. The accelerati­on began in the middle of the 20th century and it is what people call progress. We live longer, richer lives, consume a wider variety of things, but need to ask ourselves what the effects of our lifestyle are on Earth and the ecosystems of our home planet.”

The current climatic conditions disrupt what Will called the planet’s “sweet spot” which began around 12,000 years ago and led to the developmen­t of human civilisati­on and agricultur­e.

While human-influenced changes began with the early industrial­isation, it was in the last 70 years that the biggest spike in climate change occurred, creating extreme conditions, including those which led to the recent devastatin­g fires in Australia.

“Warmer temperatur­es are generated by us and we are at a critical point. The Earth is giving us unequivoca­l messages that it is destabilis­ing.” Those messages include dying coral reefs, ice loss at the poles, permafrost melting in Siberia and the Atlantic Ocean current slowing.

“What is needed is Earth System stewardshi­p, in which humans look after the planet like Ma-ori did in New Zealand and the Aboriginal people did in Australia.

“We need to learn from the people who went before us – not about how to get wealthier and wealthier, but how to become stewards of our planet. If we don’t get that right, our pathway is taking us towards the ‘planetary cliff’, beyond which lies “Hothouse Earth”, a state of Earth that will not be possible to get out of for many thousands of years.

“So, we have got real choices, big challenges and risks. Emissions in 2019 were the highest on record. So far, we are utterly failing at meeting the climate challenge. Scientists have been saying for 20 years something has to change. Five years ago, they said if we don’t get there by 2020 we’re in trouble.well its 2020 and we haven’t got there. Maybe we can just squeak through the crisis if we get greenhouse gas emissions trending steeply downward.

“We are at a critical point. We know exactly what we have to do and the challenge ahead for our beautiful planet is how we create sustainabl­e systems.”

“We are at a critical point. We know exactly what we have to do and the challenge ahead for our beautiful planet is how we create sustainabl­e systems.”

 ??  ??
 ??  ?? Will Steffen
Will Steffen

Newspapers in English

Newspapers from New Zealand