Global temperatures have stayed pretty steady for centuries until the Industrial revolution where burning of fossil fuels (coal, gas, oil) produced C02 and methane gases, that allow the sun’s heat into the earth’s atmosphere, but not out. Since then temperatures have increased roughly 1%, accelerating in the past 50 years, amplified by a reduction in the buffering effect of both sea ice and large Forested areas. Forests serve to help absorb carbon from the atmosphere and lock it in the ground, which helps, but they release carbon when burnt. Ice reflects the sun’s heat, whereas water which is darker absorbs it, warming the water and causing more ice-to melt.
By 1990 emissions had risen to 350ppm (what climate scientists classify as the safe upper limit), and in 2015 400ppm was reached (World Meteorological Org).
The last time this happened (3 million years ago), sea levels rose 10-20 metres; consistent with the observed rates of ice loss in Antarctica and Greenland today. 450ppm is deemed cataclysmic, and we’ll reach that within 25 years if we carry on our present track of adding, annually, 10 billion cubic tonnes of CO2 to the atmosphere.
Temperatures. 2016 was the hottest ever record, according to a European climate agency and a US-based climate centre, Copernicus Climate Change Service (C3S) ,0.2C warmer than 2015. Temperatures are now at the 1.5C limit (above pre-industrial levels), the parameter the globe must stay within, in order to significantly reduce the risks and impacts of climate change.
Rising sea-level. Because of large areas of ice melting, seas will rise around the globe. NZ’s coastlines face a rise of between 0.6-1.5m over the next 100 years, threatening 9,000+ homes that lie less than 50cm above spring high-tide levels.
Sea Ice. Dr James Renwick of Victoria University has been tracking levels of sea ice in the Arctic and Antarctica, and states that the Arctic ice has been rapidly decreasing and is now 40 per cent less ice in late summer than it did in the 1980s. This is important as ice reflects the sun’s heat from the earth, and without it the planet warms at a far greater rate.
As well as higher temperatures and rising seas, the NZ Ministry for the Environment outline likely impacts for NZ including:
- Threats to Biodiversity, including
- a change in rainfall patterns – with increased summer rainfall in the north and east of the North Island and increased winter rainfall in many parts of the South Island.
- more frequent extreme weather events – such as droughts (especially in the east of New Zealand) and floods, and flash flooding as drainage systems become overloaded.
- Warmer temperatures will alter habitats that are critical to some species, increasing the risk of localised extinction.
- Warmer temperatures will favour conditions for many exotic species as well as the spread of disease and pests, affecting both fauna and flora.
- Increased summer drought will put stress onto dry lowland forests.
- Earlier springs and longer frost-free seasons could affect the timing of bird egg-laying and the emergence, first flowering and health of leafing or flowering plants.
- Agricultural productivity is expected to increase in some areas but there are risks of drought and spreading of pests and diseases.
- There are likely to be costs associated with changing land-use activities to suit a new climate.
- Business and Finance
- Households may find it more difficult to access adequate insurance cover in the face of increased flood risk.
- Fruit and vegetable growers may find it more expensive to insure against weather related damage (eg, from hail).
- The risk management of potential climate change impacts may provide significant opportunities for businesses.
Global changes also include: Huge food and water shortages and likely conflict over resources. Species loss. Already 60% species worldwide have been lost. Extreme weather events , with threat to life and disruption to economies. Challenges to poorer countries who need greater energy production to provide for growing populations.
Wealthier countries, who have created much of the greenhouse gases thus far, owe it to these nations to lead the way in moving away from fossil fuels to sustainable energy forms, and help them to transition also. This requires action now, and you can help. See page on ‘what can be done’.
Journalist, Bridget Freeman- Rock gives further info in her article in Hawkes Bay paper (Bay Buzz Jan/Feb 2016)
- In a “holy shit moment for climate change”, the West Antarctic Ice Sheet was assessed in 2014 as in a state of irreversible decline, while in 2015 a team of oceanographers discovered the East Antarctic Ice Sheet, long thought to be more stable, is also melting. Sea-rise projections may have to be scaled up considerably.
- The Tasman glacier (NZ’s largest and longest) is shrinking so fast, it’s expected to disappear by the end of the century. Diminishing snowmelt and glaciers around the world will hugely impact drinking water and agriculture.
- NZ’s coastlines face rising sea levels that are up to 10% higher than the global average – between 0.6-1.5m over the next 100 years. 9,000+ homes lying less than 50cm above spring high-tide levels.
- Oceans, which soak up 90% of the extra heat in the atmosphere, are getting hotter and more acidic due to CO2 absorption (about a million tons every hour, every day). Oceans are about 40% more acidic than they were 200 years ago. Oceanographers warn: “the current rate and magnitude of ocean acidification are at least ten times faster than any event in the past 65 million years… Given that periods of rapid acidification over tens of thousands of years – slow by our current human-driven standard – resulted in mass extinction and ecological collapse, this alone should be reason to act.”
- 5C warming will lead to 97% of Australia’s Great Barrier Reef bleaching; 2C spells coral death. Coral and shellfish are particularly affected by the increasing warmth and acidity of oceans.
- 5C rise will see 25% of Earth’s animals and plants disappear.
- NZ’s canary in the mine: our native red-billed gull, subject of one of the world’s longest studies, have been in steep decline (down from 19,000 to 9,000) since the ‘population crash’ of 1994, due mainly to the depletion of the krill they depend on to feed their young and changing oceanic conditions.
- Pine bark beetles have chewed through 4 million acres of spruce trees in Alaska since 1997. Milder winters, longer summers means the beetles complete 2-3 reproductive cycles instead of one. With climate change, boreal forests are weakened by drought and more prone to deadly infestations; there are massive forest die-offs already happening in the northern hemisphere. While in NZ, 200-300 native alpine species are on track for extinction due to drier warmer conditions.
- Recent Wairau and Waikakaho Valley fires in Marlborough are estimated to cost tens of millions of dollars. Wildfires in the drier regions of NZ are set to increase 400-700% over the coming century.
- Lakes are warming globally on average by 0.34C a decade – at a greater rate of increase than either the oceans or atmosphere – with dramatic effects on human health. Algae blooms expected to increase 20% by 2100.
Interesting article from NZ perspective also http://www.nzherald.co.nz/environment/news/article.cfm?c_id=39&objectid=11552427