Paris climate targets aren’t enough, but we can close the gap

Malte Meinshausen, University of Melbourne

The Paris climate agreement saw countries pledge to limit global warming to well below 2℃, and to aim to keep it within 1.5℃. The problem is that countries’ current emissions targets are not enough to meet these goals.

In a paper published today in Nature, I and my colleagues from Austria, Brazil, China, South Africa, Germany, the Netherlands and Switzerland take a closer look at those pledges, and the studies that have so far evaluated them. The bottom line is that under the existing Paris pledges the world would be facing 2.3-3.5℃ of warming by 2100.

The pledges, known as Intended Nationally Determined Contributions or INDCs, would result in emissions 14 billion tonnes higher than they should be in 2030 under the cheapest pathway to limit warming.

While this path is well below the “business as usual” scenario, it is not yet in the range of the 1.5-2℃ objectives we have set ourselves. So it’s a first step, but bigger steps are needed.

The less effort we make before 2030, the harder it will be to reduce emissions afterwards. However, my colleagues and I have found there are several ways to close the gap.

Why do the current targets make it harder after 2030?

To limit global warming to any level, we ultimately have to completely stop CO₂ emissions and ramp down other greenhouse gas emissions. For any given warming threshold, we have to limit total emissions to a certain amount, known as the “carbon budget”.

It is likely that to keep warming well below 2℃ we have a remaining carbon budget of between 750 billion and 1.2 trillion tonnes. For context, global emissions in 2010 were around 50 billion tonnes.

Remaining on the current path, as laid out by the INDCs, would mean the world would have to make very drastic cuts in emissions after 2030 to keep warming below 2℃ (and would likely make the 1.5℃ limit completely unachievable).

This dramatic cut would mean a lot of stranded investments, as emissions will have continued to rise up to 2030, suggesting continued investment in infrastructure that won’t deliver our long-term target. The same potentially goes for any investments in “transition” fuels, such as gas. If current investments cannot be part of a 2050 world that is close to zero emissions, then they would probably have to be retired before their usual use-by date.

If in 2030 there is a sudden realisation that we have to do more, the world would have to cut emissions by 3-4% each year. Countries like Australia would have to cut them by 10% each year. It’s like walking slowly up to a cliff and then jumping off it.

This is not the cheapest way to keep warming below 2℃. The least-cost option is to start investing now in the right technology. The International Energy Agency has argued that if we want a zero-carbon economy in 2050, or at least one that is close to zero-carbon, we need to make zero-emission investments today, because it takes a long time to turn over the existing investment stock.

The other problem is carbon capture and storage (CCS). The Paris Agreement pledges net zero greenhouse gas emissions after 2050. There is no pathway to this that doesn’t involve “net-negative” emissions, because there will still be some greenhouse gas emissions we can’t reduce, and we will have already overshot the carbon budget for keeping warming below 2℃, let alone 1.5℃. So we are going to have to come up with a way to pull CO₂ from the atmosphere.

How can we do that? The main option is thought to be bio-energy with carbon capture and storage (BECCS). This process involves growing biomass fuel, such as trees, then using the woodchips to produce electricity, then capturing the CO₂ produced, and finally sequestering and storing it underground.

In the past, CCS has been mostly combined with fossil fuels. But the dramatic fall of wind and solar costs will make it easier to decarbonise the electricity sector.

CCS would also likely require a carbon price, to incentivise the necessary investment in CCS by 2030. Retrofitting existing fossil fuel power plants with CCS or keeping coal demand high by supporting new coal power plants with CCS in India and China is hence likely an uphill battle that is lost on economic grounds. However, we would still need CCS and specifically BECCS to remove CO₂ from the atmosphere.

So how can we close the gap?

Our study has found several ways to reduce emissions further before 2030.

The first is to ratchet up the INDCs by using the review mechanism built into the Paris Agreement. This is thought by many to be the single most important element of the agreement, and would see INDCs revised and increased every five years. Of course these increases would have to be underpinned by domestic policies.

Some countries will overachieve their INDCs. China, for instance, has pledged to peak its emissions by 2030, but seems to have the domestic policy in place to get there before 2020 given the concern about clean air.

Other countries have pledged emission levels that are so generously high that they would have to spend serious amounts of money to increase their emissions up to those levels. Turkey, Ukraine, Russia are examples. There are likely a billion tonnes of projected emissions that we will hence never get to see. Fortunately.

The INDCs could also be expanded to cover other greenhouse gases (which aren’t included by some countries), such as nitrous oxide and methane in China.

International shipping and aviation could also play a huge role. Aviation is one of the hardest nuts to crack because of the difficulties of producing sustainable, carbon-neutral jet fuel. So while the near-term emissions reductions options aren’t as big as many people think, these high-value sectors are hugely important because they can help to raise resources for mitigation action elsewhere.

For instance, the International Civil Aviation Organisation’s pledge of no-carbon growth after 2020 would require large offsets. This could unleash a lot of action, and transfer finance to other sectors.

However, both aviation and maritime transport need to part of the whole framework – and given that the Paris Agreement mentions all global emissions in its Art. 4.1, they are already included to some extent.

We found other initiatives – in the business sector and at regional and municipal levels – that could reduce emissions by a further 1 billion tonnes each year by 2030. However, more recent research suggests this could be as high as 6-11 billion tonnes each year, if all those additional initiatives in the solar energy, wind energy, forestry and methane sectors were implemented.

For instance, Europe’s solar and wind initiatives, if both implemented, could increase Europe’s target of 40% below 1990 levels by 2030 to 60%.

And the United States’ Sunshot and wind programs could overshoot its current emissions target, from 26-28% below 2005 levels to a staggering 60%.

These initiatives would put us well on the path to keeping warming below 2℃. Now we just have to get serious about it.

In Australia, we have neither an ambitious enough 2020 or 2030 target, nor the policies to get there. Current emissions are likely to overshoot the -5% target by 2020 (although accounting options to use previously banked credits will likely keep Australia compliant with its Kyoto Protocol targets).

There are good signs – such as state renewable energy targets, which now add up to more than the national target. And there is an immense opportunity for Australia in a zero carbon world: no other developed country is so blessed with solar and wind resources.

If Australia plays its cards right, it could become the energy superpower in a zero carbon world. But there’s still a way to go.

The Conversation

Malte Meinshausen, A/Prof., School of Earth Sciences, University of Melbourne

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


The Earth’s biodiversity could be much greater than we thought

Mike Lee, Flinders University and Paul Oliver, Australian National University

After centuries of study, you’d think we’d have at least a rough idea of how many different species of life exist on Earth. This is becoming even more pressing as biodiversity disappears at an increasing pace due to human impacts. Some species are going extinct even before we discover them.

Scientists have named nearly 2 million species, but the estimated total number out there has ranged from 3 million to 100 million. Consensus recently congealed around the lower end of this range, with one widely touted study proposing a precise figure of 8.7 million species (excluding bacteria strains, which are too tricky to count).

If so, we’ve made sizeable inroads into cataloguing the planet’s biodiversity, with perhaps 20% done.

But in correspondence published in Nature this week, we suggest this consensus may underestimate the Earth’s biodiversity by a factor of ten.

If so, the task of describing and understanding biodiversity is far more Herculean than ever imagined. In the 300 years since the Swedish naturalist Carolus Linnaeus pioneered scientific classification, we might have managed to recognise only 2% of Earth’s biodiversity.

Species are often not what they seem to be

Species are one of the fundamental units of biodiversity. Each species represents an independent evolutionary lineage and irreplaceable gene pool.

For example, the domestic dog, Canis lupus, is a separate species from the golden jackal, Canis aureas, since these two groups do not normally interbreed nor exchange genes. But spaniels and dalmatians are merely different breeds of the same species, Canis lupus, which can readily get together to produce mongrels.

Sometimes different species can be hard to tell apart. An extreme case involves cryptic species. These are separate species that are very similar outwardly, yet are true species that never interbreed. They thus possess distinct gene pools evolving in independent directions.

Cryptic species are often revealed only by laborious studies that integrate fieldwork, ecology and genetics.

Our DNA studies on what appeared to be widespread single species of Australian gecko revealed that each consists of up to ten cryptic species. Each is restricted to a small region, never interbreeding with adjacent regions at any time over the last 10 million years.

DNA from the tiny Clawless Gecko Crenadactylus from northern Australia shows it was not one but at least ten different species; eight are shown here.
Brad Maryan (Western Australian Museum), Glenn Shea (University of Sydney), and Glenn Gaikhorst

Despite looking very alike, these cryptic gecko species are much more genetically distinct from each other than, say, humans and chimps. So they are definitely proper species, despite being very similar in appearance (sometimes almost indistinguishable).

Cryptic species have recently been found in some of the biggest and well-studied marine creatures such as beaked whales and hammerhead sharks.

On land, scientists have only just realised that African elephants are probably not a single species but two cryptic species: a bush (savannah) elephant and a forest elephant.

The African bush elephant, Loxodonta africana.
Michael Lee (Flinders University and South Australian Museum)
The African forest elephant, Loxodonta cyclotis.
Richard Ruggiero/USFWS

Most of life consists of small invertebrates, especially arthropods – such as insects, spiders and crustaceans – which are much more poorly known than elephants and sharks.

With so few taxonomists and so many invertebrates, only very obviously different groups are picked out as separate species. This sorting is usually based on visual inspection alone, with no genetic analysis. These first-pass species are known as morphospecies and they make up the bulk of known biodiversity.

When scientists take a closer look at invertebrate morphospecies using DNA methods, they usually find multiple species. These might look rather similar, but never interbreed and haven’t done so for millions of years.

For example, what was once thought to be a single species of malaria-carrying mosquito turned out to be at least seven different species. A major agricultural pest (the tobacco whitefly) was revealed to be 31 cryptic species.

Biodiversity bites back! The malaria-carrying mosquito, Anopheles gambiae, turned out to be at least seven distinct species.
CDC/James Gathany

Looking at every known species in such genetic detail will be an immense task, even given the promise of techniques such as rapid DNA barcoding. But when we do so, cryptic species should prove to be the rule, rather than the exception, across the majority of life.

Millions more species

Most of the 2 million known species are morphospecies. The prediction that there are 8.7 million species on Earth, and other similar estimates, are extrapolations from this 2 million figure (or lower earlier figures such as 1.2 million).

Yet, a torrent of new genetic evidence indicates that many currently known morphospecies could represent up to ten or more cryptic species, all very similar to one another but nevertheless real species with separate gene pools. Most estimates of global species diversity have not accounted for this.

Hence, the 2 million morphospecies already described could easily turn out to represent perhaps 20 million real species, if we ever get around to analysing their DNA. This tenfold increase would swell estimates of Earth’s total biodiversity by a similar magnitude, e.g. from 8.7 million to 87 million.

Why taxonomy is vital for humanity

Does it really matter? Are there any consequences to treating, for example, African elephants as one morphospecies, or properly recognising them as two similar yet distinct species?

We think there can be profound consequences. Lumping all African elephants into a single species could lead to terrible conservation decisions.

For example, we might not be concerned that elephants in the forest were declining, as long as plenty remained on the savannah. Forest elephants might be allowed to perish, leading to the loss of a distinct species. We might compound the problem by translocating elephants from the savannah into dense forest, a foreign habitat for this species, and wonder why they weren’t thriving.

Similarly, knowing whether a pesky mosquito is one species or several is crucial information that can improve millions of lives. Cryptic mosquito species can differ in behaviour, habitat and ability to transmit malaria.

The ongoing efforts to properly count and identify the species on Earth are therefore much more than an obscure academic exercise.

Knowing how many life forms exist on Earth is one of the most fundamental scientific questions that can be asked. Our efforts to answer it will greatly benefit humanity in diverse and important ways, from conservation to agriculture to health.

The Conversation

Mike Lee, Professor in Evolutionary Biology (jointly appointed with South Australian Museum), Flinders University and Paul Oliver, Postdoctoral Researcher in Biodiversity and Evolution, Australian National University

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