Climate explained: why we need to focus on increased consumption as much as population growth


Thomas La Mela/Shutterstock

Glenn Banks, Massey University


CC BY-ND

Climate Explained is a collaboration between The Conversation, Stuff and the New Zealand Science Media Centre to answer your questions about climate change.

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Almost every threat to modern humanity can be traced simply to our out-of-control population growth (think about arable land going to housing; continued growth in demand for petroleum fuels). Is anything being done to contain population growth on a national and international scale?

The question of population is more complex that it may seem – in the context of climate change as well as other issues such as biodiversity loss and international development.

As a starting point, let’s look at the statement “out-of-control population growth”. In fact, population growth is more “in control” than it has been for the past 50 years.




Read more:
Climate explained: how growth in population and consumption drives planetary change


Population isn’t growing everywhere

The global rate of population growth has been declining from just over 2% per year in 1970 to less than 1.1% in 2020 (and this estimate was made before COVID-19 erupted globally).

To put this in perspective, if the 2% growth rate had continued, the world’s population would have doubled in 35 years. At a 1.1% growth rate, it would now be set to double in 63 years – but the growth rate is still declining, so the doubling time will be lengthened again.

Population growth also varies significantly between countries. Among the 20 most populous countries in the world, three countries have growth rates of more than 2.5% – Ethiopia, Nigeria and the Democratic Republic of Congo – while Japan’s population is in decline (with a negative growth rate, -0.3%) and China, Russia, Germany and Thailand all have very low growth rates.

These growth rates vary in part because the population structures are very different across countries. Japan has an aged population, with 28% over 65 years and just 12% under 15 years. Nigeria has only 3% of people in the over-65 bracket and 44% under 15.

For comparison, 20% of New Zealanders are younger than 15 and 16% are older than 65. For Australia, the respective figures are 18% and 17%.

Migration also makes a significant contribution in some countries, propping up the working-age population and shaping the demographic structure. History and levels of economic development play an important role too: higher-income countries almost consistently have smaller families and lower growth rates.

Rise in consumption

It’s certainly valid to link population growth (even a more limited “in control” population growth) with climate change and loss of land. Everything else being equal, more people means more space taken up, more resources consumed and more carbon emitted.

But while population growth has slowed since the 1970s, resource consumption hasn’t. For example, there is no equivalent decline in fossil fuel use since the 1970s.

Fuel consumption varies throughout the world.
Flickr/Minnesota Pollution Control Agency, CC BY-NC

This is an area where not everyone is equal. If all people were to use the same amount of resources (fossil fuels, timber, minerals, arable land etc), then of course total resource use and carbon would rise. But resource use varies dramatically globally.

If we look at oil consumption per person in 2019, the average American used almost twice as much as someone in Japan, the second oil-thirstiest populous nation, and almost 350 times as much as a person living in the Democratic Republic of Congo.

It is an easy out for us in the industrialised world to say “out-of-control population growth” is killing the planet, when instead it is equally valid – but more confronting – to say our out-of-control consumption is killing the planet.




Read more:
Can your actions really save the planet? ‘Planetary accounting’ has the answer


Population growth slows when women are educated

To come to the final part of the question: is anything being done to contain population growth, on a national or international scale?

Even if we set aside the argument above that population is not the only issue, or even the most significant one, in terms of threats to humanity, what factors might influence population growth in parts of the world where it is high?

Things are being done, but they may not be what most people expect. It has long been shown that as incomes rise and health care improves, more children survive and people tend to have smaller families.

This effect is not instantaneous. There is a lag where population growth rates might rise first before they begin to drop. This demographic transition is a relatively consistent pattern globally.

But, at the country level, the single most significant influence on reducing fertility rates, family size and overall population growth is access to education for girls and women.

Fertility rates drop when girls get access to education.
Oksana Kuzmina/Shutterstock

One study in 2016, drawing on World Bank population data across a wide range of countries, found:

… the main driver of overall fertility reduction is clearly the change in proportions of women at each education level.

In relation to climate change action, this study specifically notes:

It is education, or more specifically girls’ education, that is far more likely to result in lower carbon emissions than a shift to renewables, improved agricultural practices, urban public transport, or any other strategy now being contemplated.

Recent research looked at how the global population might change if we implemented the aspirations of the 17 UN Sustainable Development Goals. It found the change would be significant and could even mean the global population stabilises by mid-century.The Conversation

Glenn Banks, Professor of Geography and Head of School, School of People, Environment and Planning, Massey University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Contributions to sea-level rise have increased by half since 1993, largely because of Greenland’s ice



File 20170625 13461 lezup7
Water mass enters the ocean from glaciers such as this along the Greenland coast.
NASA/JPL-Caltech

John Church, UNSW; Christopher Watson, University of Tasmania; Matt King, University of Tasmania; Xianyao Chen, and Xuebin Zhang, CSIRO

Contributions to the rate of global sea-level rise increased by about half between 1993 and 2014, with much of the increase due to an increased contribution from Greenland’s ice, according to our new research.

Our study, published in Nature Climate Change, shows that the sum of contributions increased from 2.2mm per year to 3.3mm per year. This is consistent with, although a little larger than, the observed increase in the rate of rise estimated from satellite observations.

Globally, the rate of sea-level rise has been increasing since the 19th century. As a result, the rate during the 20th century was significantly greater than during previous millennia. The rate of rise over the past two decades has been larger still.

The rate is projected to increase still further during the 21st century unless human greenhouse emissions can be significantly curbed.

However, since 1993, when high-quality satellite data collection started, most previous studies have not reported an increase in the rate of rise, despite many results pointing towards growing contributions to sea level from the ice sheets of Greenland and Antarctica. Our research was partly aimed at explaining how these apparently contradictory results fit together.

Changes in the rate of rise

In 2015, we completed a careful comparison of satellite and coastal measurements of sea level. This revealed a small but significant bias in the first decade of the satellite record which, after its removal, resulted in a slightly lower estimate of sea-level rise at the start of the satellite record. Correcting for this bias partially resolved the apparent contradiction.

In our new research, we compared the satellite data from 1993 to 2014 with what we know has been contributing to sea level over the same period. These contributions come from ocean expansion due to ocean warming, the net loss of land-based ice from glaciers and ice sheets, and changes in the amount of water stored on land.

Previously, after around 2003, the agreement between the sum of the observed contributions and measured sea level was very good. Before that, however, the budget didn’t quite balance.

Using the satellite data corrected for the small biases identified in our earlier study, we found agreement with the sum of contributions over the entire time from 1993 to 2014. Both show an increase in the rate of sea-level rise over this period.

The total observed sea-level rise is the sum of contributions from thermal expansion of the oceans, fresh water input from glaciers and ice sheets, and changes in water storage on land.
IPCC

After accounting for year-to-year fluctuations caused by phenomena such as El Niño, our corrected satellite record indicates an increase in the rate of rise, from 2.4mm per year in 1993 to 2.9mm per year in 2014. If we used different estimates for vertical land motion to estimate the biases in the satellite record, the rates were about 0.4mm per year larger, changing from 2.8mm per year to 3.2mm per year over the same period.

Is the whole the same as the sum of the parts?

Our results show that the largest contribution to sea-level rise – about 1mm per year – comes from the ocean expanding as it warms. This rate of increase stayed fairly constant over the time period.

The second-largest contribution was from mountain glaciers, and increased slightly from 0.6mm per year to 0.9mm per year from 1993 to 2014. Similarly, the contribution from the Antarctic ice sheet increased slightly, from 0.2mm per year to 0.3mm per year.

Strikingly, the largest increase came from the Greenland ice sheet, as a result of both increased surface melting and increased flow of ice into the ocean. Greenland’s contribution increased from about 0.1mm per year (about 5% of the total rise in 1993) to 0.85mm per year (about 25% in 2014).

Greenland’s contribution to sea-level rise is increasing due to both increased surface melting and flow of ice into the ocean.
NASA/John Sonntag, CC BY

The contribution from land water also increased, from 0.1mm per year to 0.25mm per year. The amount of water stored on land varies a lot from year to year, because of changes in rainfall and drought patterns, for instance. Despite this, rates of groundwater depletion grew whereas storage of water in reservoirs was relatively steady, with the net effect being an increase between 1993 and 2014.

So in terms of the overall picture, while the rate of ocean thermal expansion has remained steady since 1993, the contributions from glaciers and ice sheets have increased markedly, from about half of the total rise in 1993 to about 70% of the rise in 2014. This is primarily due to Greenland’s increasing contribution.

What is the future of sea level?

The satellite record of sea level still spans only a few decades, and ongoing observations will be needed to understand the longer-term significance of our results. Our results also highlight the importance of the continued international effort to better understand and correct for the small biases we identified in the satellite data in our earlier study.

Nevertheless, the satellite data are now consistent with the historical observations and also with projected increases in the rate of sea-level rise.

Ocean heat content fell following the 1991 volcanic eruption of Mount Pinatubo. The subsequent recovery (over about two decades) probably resulted in a rate of ocean thermal expansion larger than from greenhouse gases alone. Thus the underlying acceleration of thermal expansion from human-induced warming may emerge over the next decade or so. And there are potentially even larger future contributions from the ice sheets of Greenland and Antarctica.

The ConversationThe acceleration of sea level, now measured with greater accuracy, highlights the importance and urgency of cutting greenhouse gas emissions and formulating coastal adaptation plans. Given the increased contributions from ice sheets, and the implications for future sea-level rise, our coastal cities need to prepare for rising sea levels.

Sea-level rise will have significant impacts on coastal communities and environments.
Bruce Miller/CSIRO, CC BY

John Church, Chair professor, UNSW; Christopher Watson, Senior Lecturer, Surveying and Spatial Sciences, School of Land and Food, University of Tasmania; Matt King, Professor, Surveying & Spatial Sciences, School of Land and Food, University of Tasmania; Xianyao Chen, Professor, and Xuebin Zhang, Senior research scientist, CSIRO

This article was originally published on The Conversation. Read the original article.

Africa: Madagascar


Rare Duck Population Grows by Almost 50%

The link below is to an article reporting on the good news story of the Madagascar Pochard (Aythya innotata) duck, which until recently was thought to be extinct. Now a captive breeding program has increased the population by almost 50% in one season.

For more, visit:
http://news.mongabay.com/2012/0406-madagascar_porchard.html

Australia: Native Trees and Climate Change


The link below is to an article reporting on research into the capability of native Australian trees to cope with increased carbon dioxide as climate change accelerates.

For more, visit:
http://www.smh.com.au/environment/conservation/native-trees-put-to-the-carbon-test-20120404-1wdeg.html

Global Warming: Temperatures Rising Quicker


The link below is to an article reporting on the possibility of an increased rate of global warming than previously thought.

For more visit:
http://news.sciencemag.org/sciencenow/2012/03/earth-warming-faster-than-expected.html

Australia: Carbon Price Needed Now


Thirteen of Australia’s leading economists have signed and published an open letter calling for a speedy introduction of a carbon price for carbon polluters. They prefer to have a carbon emissions trading scheme institututed as soon as possible.

The introduction of carbon pricing is designed to accelerate a move to more environmentally friendly production methods, increased reliance on renewable energy sources, etc.

For more visit:
http://theconversation.edu.au/economists-open-letter-calls-for-carbon-price-1639

View the actual letter.

 

Bison to Enjoy Increased Protection at Yellowstone


Having been driven to near the point of extinction, Bison have been making a come back in the United States. The article that follows deals with an increase in protected lands for migrating Bison from Yellowstone National Park, providing more good news for a species that was almost lost.

For more visit:
http://www.defendersblog.org/2011/04/big-win-for-bison/#1

NEW SOUTH WALES NATIONAL PARKS UNDER THREAT???


The New South Wales government is now considering some level of development in the national parks of New South Wales. Just what level of development that may be is yet to be made clear. It is understood that the development may include accommodation projects, various commercial enterprises and guided bush walks.

Tourism Minster Jodi McKay, a former news reader with NBN television, is waiting on a report from a government commissioned taskforce looking into ways that tourism can be increased in the state’s national parks.

The planned tourism development of national parks is a major step away from the ‘wilderness’ goals of recent times and represents a threat to the wilderness values of national parks and world heritage listed areas.

However, a certain level of development may be appropriate, given the serious deterioration of many of the amenities and signage within New South Wales national parks. Many access routes are also seriously degraded following years of poor management.

Perhaps a quality New South Wales national parks and reserves web site could be developed, with the current web site being quite dated and not particularly useful for visitors to the national parks of New South Wales. Quality information on the attractions and access to each national park would greatly improve the tourist potential of New South Wales national parks.

If quality visitor brochures/leaflets on such things as camping facilities, access routes, walking trails and park attractions could be developed and made available via PDF documents on the web site, potential visitors could plan their trips and this would certainly increase visitor numbers to the national parks.

Quality content and relevant up-to-date information on each national park, as well as well maintained access routes and facilities would encourage far more people to visit the national parks and give visitors a memorable experience.

BELOW: Footage of the Warrumbungle National Park in NSW.