No, you can’t argue the Medieval warm period is evidence that today’s climate change isn’t all that bad

23 04 2021
As this reconstructed village shows, Vikings made it as far as Newfoundland during the Medieval warm period. Wikimedia/Dylan Kereluk, CC BY-SA

Frédérik Saltré, Flinders University and Corey J. A. Bradshaw, Flinders University

What was the Medieval warm period? What caused it, and did carbon dioxide play a role?

We are living in a world that is getting warmer year by year, threatening our environment and way of life.

But what if these climate conditions were not exceptional? What if it had already happened in the past when human influences were not part of the picture?

The often mentioned Medieval warm period seems to fit the bill. This evokes the idea that if natural global warming and all its effects occurred in the past without humans causing them, then perhaps we are not responsible for this one. And it does not really matter because if we survived one in the past, then we can surely survive one now.

But it’s just not that simple.

Read more: 2,000 years of records show it’s getting hotter, faster

The Medieval climate anomaly

This Medieval period of warming, also known as the Medieval climate anomaly, was associated with an unusual temperature rise roughly between 750 and 1350 AD (the European Middle Ages). The available evidence suggests that at times, some regions experienced temperatures exceeding those recorded during the period between 1960 and 1990. Read the rest of this entry »


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Categories : agriculture, anthropocene, Arctic, Asia, Australia, carbon, Central America, climate change, climate shift, drought, Europe, New Zealand

Climate explained: humans have dealt with plenty of climate variability

23 09 2020
© Professor John Long, Flinders University, Author provided

(originally published on The Conversation)

 

How much climate variability have humans dealt with since we evolved and since we started settling (Neolithic times)? How important was migration to human survival during these periods?

 

The climate always fluctuates as variation in the Sun’s heat reaching Earth drives glacial-interglacial cycles. Over the past 420,000 years there have been at least four major transitions between ice ages and relatively warmer interglacial periods.

Modern humans emigrated from Africa to populate the rest of the globe between 120,000 and 80,000 years ago, which means our species has had to adapt to many massive climate transitions.

 

Warming and cooling

The Last Interglacial 129,000–116,000 years ago was a period of intense global warming (from around 2 ℃ higher than today to as much as 11 ℃ higher in the Arctic), leading to a large reduction of the Arctic, Greenland and Antarctic ice sheets, and a 6–9 m rise in sea level.

The front of a glacier breaking away and falling into the sea.
Arctic glaciers have melted before. Flickr/Kimberly Vardeman, CC BY

The Last Glacial Maximum from 26,500–19,000 years ago coincided with a large drop in atmospheric CO₂ and a 4.3 ℃ cooling globally.

Read more: Climate explained: will the tropics eventually become uninhabitable?

 

Low temperatures turned much of the world’s water into ice and expanded glaciers.

Read the rest of this entry »

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Buying time

27 06 2016

farmOriginally published in the Otago Daily Times by Tom McKinlay

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If we don’t act soon, the world we leave our children will be in a sorry state indeed, leading Australian scientist Prof Corey Bradshaw tells Tom McKinlay.

Prof Corey Bradshaw’s 9-year-old daughter lives what sounds an idyllic existence. On their small farm outside Adelaide in South Australia, she has her chickens and her dogs and her cats, her goats and her sheep.

She’s an only child, but is not short of attention from adults and reads voraciously.

She has big plans; there are at least 25 careers she likes the look of, that she’ll undertake simultaneously: farmer, wildlife rescuer, self-sufficient bush dweller – feeding herself by shooting arrows at fish – scientist and more.

She is optimistic about the future. As she should be. A 9-year-old girl living in Australia in 2016 should regard the sky as no limit at all.

All this I learn from her father, ecologist Prof Bradshaw, who talks of his daughter with an enthusiasm unbounded.

It is fair to assume she has picked up some of her interest in the natural world from him.

He holds the Sir Hubert Wilkins Chair of Climate Change in the School of Biological Sciences at the University of Adelaide.

And the ecologist, conservation biologist and systems modeller – with a University of Otago degree – has shared a great deal of his work with his daughter.

“She’s very much a farm kid, but because of who I am she gets to hear a lot about animal and plant systems around the world, and she’s travelled a lot with me and she’s a complete fanatic of David Attenborough,” the professor says.

So far, still so idyllic. But Prof Bradshaw’s work means he is at the forefront of alerting the world to what is not right with it.

Pollution, climate change, habitat loss, extinction.

His daughter has travelled with him to see species that might not be with us by the time she grows up.

“She’s hyper-aware of extinctions, in particular, and how climate change is contributing to that,” Prof Bradshaw says.

“I don’t pull any punches with her.”

In fact, he made her cry when she was 5 explaining climate change. She hasn’t needed to travel to know the pot is on the boil. Fires have forced the family to flee its South Australian property several times, not just at the height of summer.

One of the worst fires in the region struck in May a couple of years back.

“We were on the doorstep of winter and we had one of our worst fires in 20 years.”

So even without a scientist in the family, there are certain unavoidable truths for a child growing up in 21st-century Australia.

Prof Bradshaw is coming to Dunedin next month as part of the New Zealand International Science Festival to talk on climate change, looking at it from his daughter’s perspective. Read the rest of this entry »


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Categories : agriculture, Australia, biodiversity, biowealth, climate change, climate shift, conservation, development, environmental policy, extinction, food, habitat loss, health, human overpopulation, New Zealand, poverty, science

Food for sex

18 03 2013
Quercus_KakFeed Photo
Kakapo are unique among the ~ 400 parrot species (Psittaciformes) for being flightless, nocturnal and extremely long-lived (up to 100 years!). Additionally, they are herbivorous (seeds, fruits, polen, plants), males can weigh up to 2-4 kg (40% heavier than females), and females lay their eggs on the ground or cavities – i.e., 3 eggs in a single clutch annually, although 2 clutches might occur if the nest fails at the beginning of the reproductive season or if the eggs are taken for artificial incubation.Native to New Zealand, kakapo once inhabited the subalpine fringes of forest and scrub. Polynesians (1000 years ago) and Europeans (mostly in the XIX Century) arrived in the archipelago accompanied by dogs, cats, rats and mustelids that cornered kakapo populations in the Fiordland region (south-west of the South Island) where it was declared extinct in 1989. In 1977, a population of some 200 individuals was found on Stewart Island – this population was already in decline to the claws and jaws of feral cats. By the 1980s, the failure of captive breeding programs prompted the transfer of 60 individuals from Steward to carnivore-free islands. The global (known) population ‘rocketed’ from 50 individuals in 1999 to 126 in the 2012 censuses and, consequently, the kakapo’s IUCN status changed in 2000 from ‘Extinct in the Wild’ to ‘Critically Endangered’. Under the management of the Kakapo Recovery Programme, kakapo are now present on the islands of Codfish, Anchor and Little Barrier.

Inbreeding, system shocks caused by fire or cyclones (for example), or demographic stochasticity (by which two or more outcomes are possible) such as how many males and females will be born in a single year, are all factors that threaten the persistence of small and fragmented populations. They can, however, be reverted by conservation actions.

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If you have ever taken dancing classes, you will be familiar with the scarcity of male partners and how this can jeopardize group learning. When reproduction, rather than salsa pirouettes, is at stake, a biased sex ratio can compromise the persistence of species. For instance, when females are unable to find males (or vice versa), fertility rates can collapse as a result – a well-known cause of an Allee effect (1). Curiously, natural selection can promote such bias by favouring a species’ investment in litters dominated by one of the two genders. The evolutionary formulation of such scenario is that females can adjust the sex ratio of their offspring depending on the amount of available resources (2) – see contrasting cross-taxa studies on this subject (3-5). Thus, when resources abound (e.g., food), mothers can afford the offspring’s gender requiring more resources to reach adulthood or once adulthood is reached, is less likely to reproduce successfully (6). This predisposition to one gender or another can be key to the conservation of endangered species (7).

The kakapo case

At the end of the 1990s, the New Zealand Department of Conservation placed dispensers of supplementary food in the territories of some kakapo (a rather enormous, flightless parrot Strigops habroptilus) to encourage their reproduction. Back then, only 60 individuals were left of the entire species . Unfortunately, those females with access to the supplemental food conceived 67% of male chicks (so exacerbating the fact that kakapo populations are naturally male-biased), while those females without extra feeding had 71% of female chicks (8). Something wasn’t working. Read the rest of this entry »


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Categories : Allee effect, captive breeding, conservation, decline, extinction, fragmentation, invasive species, kakapo, management, New Zealand, population dynamics, Red List, threatened species

Supercharge Your Science V.2

24 11 2011

I suspect a lot of ConservationBytes.com readers will be attending the imminent 25th International Congress for Conservation Biology to be held in Auckland from 5-9 December 2011 (it was to be held in Christchurch, but the venue was changed after that city fell down). I’ve now been to 3 previous ICCBs myself, and it should prove to be a good, informative (and fun) meeting.

I’ll be giving a talk or two, as will some of my students and postdocs, but I’m not spruiking those here (but you’re all invited, of course).

The main reason for this short post today is to advertise for Version 2 of our (i.e., Bill Laurance and me) popular ‘Supercharge Your Science‘ workshop. Yes, the organising committee of the ICCB decided it was a good idea to accept our application to repeat our previously successful series of presentations extolling the virtues of positive and controlled media interactions, social media and good writing techniques for ‘supercharging’ the impact of one’s science. You can read more about the content of this workshop here and here.

The description of the workshop (to be held from 19.00 – 21.00 on 6 December in the SkyCity venue) on the ICCB website is: Read the rest of this entry »


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Categories : biodiversity, conference, conservation, conservation biology, media, New Zealand, science, science communication, scientific publishing, scientific writing, words, writing tips

Few people, many threats – Australia’s biodiversity shame

31 07 2009

bridled_nailtail_400I bang on a bit about human over-population and how it drives biodiversity extinctions. Yet, it isn’t always hordes of hungry humans descending on the hapless species of this planet  – Australia is a big place, but has few people (just over 20 million), yet it has one of the higher extinction rates in the world. Yes, most of the country is covered in some fairly hard-core desert and most people live in or near the areas containing the most species, but we have an appalling extinction record all the same.

A paper that came out recently in Conservation Biology and was covered a little in the media last week gives some telling figures for the Oceania region, and more importantly, explains that we have more than enough information now to implement sound, evidence-based policy to right the wrongs of the past and the present. Using IUCN Red List data, Michael Kingsford and colleagues (paper entitled Major conservation policy issues for biodiversity in Oceania), showed that of the 370 assessed species in Australia, 80 % of the threatened ones are listed because of habitat loss, 40 % from invasive species and 30 % from pollution. As we know well, it’s mainly habitat loss we have to control if we want to change things around for the better (see previous relevant posts here, here & here).

Kingsford and colleagues proceed to give a good set of policy recommendations for each of the drivers identified:

Habitat loss and degradation

  • Implement legislation, education, and community outreach to stop or reduce land clearing, mining, and unsustainable logging through education, incentives, and compensation for landowners that will encourage private conservation
  • Establish new protected areas for habitats that are absent or poorly represented
  • In threatened ecosystems (e.g., wetlands), establish large-scale restoration projects with local communities that incorporate conservation and connectivity
  • Establish transparent and evidence-based state of environment reporting on biodiversity and manage threats within and outside protected areas.
  • Protect free-flowing river systems (largely unregulated by dams, levees, and diversions) within the framework of the entire river basin and increase environmental flows on regulated rivers

Invasive species

  • Avoid deliberate introduction of exotic species, unless suitable analyses of benefits outweigh risk-weighted costs
  • Implement control of invasive species by assessing effectiveness of control programs and determining invasion potential
  • Establish regulations and enforcement for exchange or treatment of ocean ballast and regularly implement antifouling procedures

Climate change

  • Reduce global greenhouse gas emissions
  • Identify, assess, and protect important climate refugia
  • Ameliorate the impacts of climate change through strategic management of other threatening processes
  • Develop strategic plans for priority translocations and implement when needed

Overexploitation

  • Implement restrictions on harvest of overexploited species to maintain sustainability
  • Implement an ecosystem-based approach for fisheries, based on scientific data, that includes zoning the ocean; banning destructive fishing; adopting precautionary fishing principles that include size limits, quotas, and regulation with sufficient resources based on scientific assessments of stocks and; reducing bycatch through regulation and education
  • Implement international mechanisms to increase sustainability of fisheries by supporting international treaties for fisheries protection in the high seas; avoiding perverse subsidies and improve labelling of sustainable fisheries; and licensing exports of aquarium fish
  • Control unsustainable illegal logging and wildlife harvesting through local incentives and cessation of international trade

Pollution

  • Decrease pollution through incentives and education; reduce and improve treatment of domestic, industrial, and agriculture waste; and rehabilitate polluted areas
  • Strengthen government regulations to stop generation of toxic material from mining efforts that affects freshwater and marine environments
  • Establish legislation and regulations and financial bonds (international) to reinforce polluter-pays principles
  • Establish regulations, education programs, clean ups, labelling, and use of biodegradable packaging to reduce discarded fishing gear and plastics

Disease

  • Establish early-detection programs for pathological diseases and biosecurity controls to reduce translocation
  • Identify causes, risk-assessment methods, and preventative methods for diseases
  • Establish remote communities of organisms (captive) not exposed to disease in severe outbreaks

Implementation

  • Establish regional population policies based on ecologically sustainable human population levels and consumption
  • Ensure that all developments affecting the environment are adequately analysed for impacts over the long term
  • Promote economic and societal benefits from conservation through education
  • Determine biodiversity status and trends with indicators that diagnose and manage declines
  • Invest in taxonomic understanding and provision of resources (scientific and conservation) to increase capacity for conservation
  • Increase the capacity of government conservation agencies
  • Focus efforts of nongovernmental organisations on small island states on building indigenous capacity for conservation
  • Base conservation on risk assessment and decision support
  • Establish the effectiveness of conservation instruments (national and international) and their implementation

A very good set of recommendations that I hope we can continue to develop within our governments.

CJA Bradshaw

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Categories : Australia, biodiversity, climate change, conservation, coral reefs, deforestation, disease, ecosystem function, education, environmental policy, exploitation, extinction, fish, fisheries, fragmentation, habitat loss, harvest, hotspot, human overpopulation, illegal fishing, invasive species, IUCN, IUU fishing, marine protected area, monitoring, New Zealand, protected area, Red List, research, reserve, restoration, threatened species

Failing on ocean protection

24 11 2008

A new paper from Conservation Letters by Mark Spalding and colleagues entitled Toward representative protection of the world’s coasts and oceans-progress, gaps, and opportunities reminds us just how crap we are at protecting ocean habitats. I sincerely hope this one is a Potential given that the only direction one can move from absolute bottom is up. Richard Black at the BBC reports on the paper’s main findings:

toilet-ocean_squareLess than 1% of the world’s oceans have been given protected status, according to a major survey.

Governments have committed to a target of protecting 10% by 2012, which the authors of the new report say there is no chance of meeting.

Protecting ecologically important areas can help fish stocks to regenerate, and benefit the tourism industry.

The survey was led by The Nature Conservancy (TNC) and is published in the journal Conservation Letters.

“For those of us working in the issue full-time it’s not a surprise, we’ve known all along that marine protection is lagging behind what’s happening on land, but it’s nice to have it pinned down,” said TNC’s Mark Spalding.

“It’s depressing that we’ve still got so far to go, but there are points of hope,” he told BBC News.

Coastal concentration

Four years ago, signatories to the UN’s biodiversity convention – which includes almost every country – pledged to protect at least 10% of the oceans in a way that makes sense ecologically.

Protecting them does not mean banning activities such as fishing or shipping completely, but making sure they are carried out sustainably.

All of the areas currently protected fall into countries’ Exclusive Economic Zones, and the majority are along coasts, the study finds.

Even so, only about 4% of coastal waters are protected.

Countries diverge widely in how much protection they have mandated.

Whereas New Zealand has almost 70% of its coastline under some form of protection, countries around the Mediterranean have set aside less than 2%.

In the developing world, Dr Spalding cites Guinea-Bissau as a country that has had invested in protection, particularly in the Bijagos Archipelago, which is home to a community of hippos dwelling along its mangrove coast, as well as more conventional marine species.

Palau, Indonesia, Micronesia and several Caribbean states are also making significant progress, he said.

About 12% of the Earth’s land surface has been put under protection.

Download the Spalding paper free of charge here.


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Categories : coasts, conservation, ecosystem services, environmental policy, exploitation, fisheries, harvest, marine, marine protected area, New Zealand, planning, protected area, reserve, tropical


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