Countries are taking a shortcut to net-zero emissions by including forests and other 鈥減assive鈥� carbon sinks in their climate plans, in a tactic that will thwart global efforts to halt climate change, leading researchers have warned.

Relying on natural carbon sinks to soak up ongoing carbon emissions from human activity will condemn the world to continued warming. That is according to the researchers who first developed the science behind net-zero emissions, and who have today launched a highly unusual intervention to call out nations and companies for misusing the concept.

鈥淭his paper is a call to clarify to people what was originally meant by net zero,鈥� at the University of Oxford told a press briefing on 14 November.

Natural sinks such as forests and peat bogs play a vital role in Earth鈥檚 natural carbon cycle by absorbing some of the carbon in the atmosphere. But existing sinks cannot be relied upon to offset ongoing greenhouse gas emissions.

If they are used in this way, global atmospheric concentrations of carbon dioxide will remain stable once 鈥渘et zero鈥� is reached, and warming will continue for centuries because of the way the oceans absorb heat, Allen warned. 鈥淵ou could think you are on a path of 1.5掳C, and end up with warming of well over 2掳C,鈥� he said. 鈥淭his ambiguity could, in effect, cost us the goals of the Paris Agreement.鈥�

To stop global temperatures rising, emissions need to reach net zero without relying on passive uptake by the land and oceans. This allows existing natural sinks to continue absorbing excess CO2, bringing down atmospheric concentrations of the gas and offsetting ongoing warming from the deep ocean.

However, many countries already count passive land sinks such as forests as greenhouse gas removal in their national carbon accounts. Some, including Bhutan, Gabon and Suriname, have even , thanks to their existing extensive forest cover.

Others have set long-term net-zero targets based on this approach. Russia, for example, , but the plan relies heavily on using its existing forests to absorb ongoing carbon emissions.

鈥淢aybe you will get some countries deliberately using this in a mischievous way,鈥� at the CICERO Center for International Climate Research in Oslo, Norway, told the briefing. 鈥淭his is going to be more problematic in countries with large forest areas as a share of their total land.鈥�

The team fears this issue will become more acute as carbon markets develop and the pressure on nations to decarbonise intensifies. 鈥淎s carbon becomes more valuable, the pressure to define any removal you can as a negative emission, in order potentially to be able to sell it on the carbon offset markets, will become much stronger,鈥� said Allen.

Nations and companies with net-zero targets in place should revise their approach to exclude passive carbon uptake from their account, the team says.

Natural sinks can count as carbon removal if they are additional to what already exists: for example, a new forest is planted or a peat bog is rewetted. However, these kinds of natural carbon sinks are vulnerable to climate impacts such as wildfires, droughts and the spread of invasive species, making them unreliable for long-term sequestration.

This hasn鈥檛 stopped nations from leaning heavily on these natural sinks in their net-zero strategies. One found many countries, including the US, France, Cambodia and Costa Rica, plan to rely on forest carbon or other nature-based removal to balance out ongoing emissions. 鈥淢any national strategies 鈥榖et鈥� on the increase of carbon sinks in forests and soils as a means of achieving long-term targets,鈥� the study鈥檚 authors wrote.

Natural carbon sinks must be preserved, but should not be relied on to balance out ongoing emissions, stressed Allen. Instead, he urges nations to aim for 鈥済eological net zero鈥�, which would ensure that all ongoing carbon emissions are balanced with long-term carbon sequestration in underground stores.

鈥淐ountries need to acknowledge the need for geological net zero,鈥� he said. 鈥淲hich means if you are still generating carbon dioxide from burning fossil fuels by mid-century, you need to have a plan to put the carbon dioxide they generate back into the ground.鈥�

鈥淕eological net zero seems a sensible global goal for countries to aim for,鈥� says at the University of East Anglia, UK. 鈥淚t helps clarify a lot of the ambiguity that plagues the way countries currently account for removals on land.鈥�

But that could have knock-on consequences for climate ambition, he warns. 鈥淲hat might the new politics of geological net zero be? How might this impact the climate ambitions of governments if geological net zero moves the goalposts on their climate strategy?鈥�

It is by now well established that to mitigate the worst effects of climate change, we need to reach net-zero carbon emissions as fast as possible. That means getting more of our energy from renewable sources and finding ways to store it for long periods to overcome the intermittency of wind and solar.

Huge battery installations and green hydrogen 鈥� where excess renewable energy is used to split water 鈥� are often touted as the most promising storage solutions, and clever new ways to hoard excess power are popping up all the time (see 鈥淕iant dome filled with CO2 could store excess power from renewables鈥�). However, the possibilities for storing renewable energy as heat are often overlooked.

When we think about renewables, we tend to think about electricity. But heat itself is also a valuable commodity. About half of the world鈥檚 total energy demand is for heat, whether for warming homes or to power the industrial production of food, medicines, materials and more. Besides, stored heat can also be used to generate electricity when the sun stops shining and the wind dies down.

The good news, as we discover in our feature 鈥淗ow incredibly simple tech can supercharge the race to net zero鈥�, is that a whole range of heat storage technologies are emerging. Known collectively as Thermal Energy Storage (TES), many of these innovations are disarmingly simple 鈥� from toasted bricks to molten salt. Crucially, they should also be affordable. Early estimates suggest that these technologies could be as little as a fifth of the cost, per kilowatt-hour, of energy storage using green hydrogen. In a recent report, the International Renewable Energy Agency said TES offers 鈥渦nique benefits鈥�.

The problem is that there is relatively little awareness of TES, and even less investment. Private backers are beginning to put serious money into pilot projects in the US and Europe. But governments everywhere need to step up if we are to make good on TES鈥檚 promise as a relatively easy way to make a hefty dint in renewable energy鈥檚 intermittency problem. If the prices are as good as they look, we can鈥檛 afford not to.

With funding from Innovate UK, the Welsh government and the UK Space Agency, UK non-profit xRI has built two of these BESS cars. Over the course of three months in 2024, the vehicles have scanned more than 1.5 million homes.

The aim is to combine the data gathered by the BESS cars with other information, including drone and satellite imagery, to build a comprehensive database on the state of the UK’s buildings. Collating this information into an AI-powered database will help councils, housing associations and other property owners more quickly design and finance big retrofit projects, the team hopes.

New 女生小视频 took an exclusive ride in a BESS car to find out more about this technology and how it can help the UK speed up the decarbonisation of its building stock.

UK city-dwellers may have spotted a strangely shaped car cruising around their neighbourhood earlier this year. It looks just like a Google Street View vehicle, with a camera rig emerging from the back end to scan its environment 鈥� and like the Google cars, it, too, is scanning and photographing city streets.

But these modified Teslas aren鈥檛 just taking photos. They are kitted out with state-of-the-art sensors and scanners that enable them to report back on the exact dimensions, heat loss, materials, age and state of dilapidation of every building they drive past.

Armed with this so-called built environment scanning system (BESS), the cars have been on the hunt to find out how leaky and run-down the UK鈥檚 building stock really is. Between March and May, they scanned thousands of streets and millions of buildings across London, Liverpool, Cardiff, Glasgow, Manchester, Leeds and South Yorkshire.

The data from the BESS vehicles is being combined with thermal imagery captured by drones and planes in a 拢4 million government-funded project to build a huge digital database detailing the state of buildings across the UK. The aim is to help housing associations, councils and other property owners quickly plan retrofit projects across hundreds of properties at once, says Ahsan Khan at xRI, the UK not-for-profit organisation behind the project.

Decarbonising the UK鈥檚 building stock is one of the trickiest challenges for the journey to net-zero emissions. The country鈥檚 30 million buildings contribute around one third of the UK鈥檚 total greenhouse gas emissions, with most of the pollution down to the use of gas to heat space and water.

Another issue is that many UK homes are old and draughty. Retrofitting these properties to become more energy efficient will be crucial, but with such huge variety in the age and condition of buildings, knowing where to start is a major challenge. 鈥淲e鈥檙e hamstrung as a nation, because we don鈥檛 quite know what we鈥檝e got, where it is and what we can do to it, in terms of the built environment,鈥� says Khan.

The only mechanism right now for judging a building鈥檚 sustainability is energy performance certificates (EPCs). These are mandatory documents that grade every building on a scale of A to G and offer owners advice on how to improve their rating. But EPCs, which rely on judgement calls made by in-person assessors, are 鈥渆xpensive, slow and inaccurate鈥�, says at Innovate UK, a government agency part-funding the project. The UK Space Agency and the Welsh government are also funders.

For organisations looking to retrofit hundreds of properties in one go 鈥� housing associations or councils, for example 鈥� EPCs are of little use. Instead, they often have to send their own assessors to properties to plan a schedule of works, an expensive and time-consuming exercise.

Speeding up retrofits

The hope is the new database will digitise much of this process. If it works as planned, it will use machine learning to tell councils how many of their properties already have double-glazed windows fitted, for example, or which houses need a top-up of cavity wall insulation. In an instant, it will be able to locate exactly which homes have the space and sunshine for rooftop solar panels. Crucially, it should be able to calculate predicted savings on energy bills, providing return-on-investment information for organisations to unlock access to green finance.

鈥淭he xRI project represents a leap forward in our understanding of the existing stock,鈥� says Mat Colmer at Innovate UK. 鈥淰erified data sets will improve and automate the process of renovation, speeding up the whole retrofit process.鈥�

With around 7.5 per cent of homes in England, Scotland and Wales scanned already, Khan says the framework is in place to build a beta version of the database, due to be released later this year. For now, xRI is focused on decarbonising buildings. But the BESS vehicles collect data on everything they see, from tree cover to potholes, which could be put to use in the future. 鈥淭he volume of data is just mind-boggling,鈥� says Pitts.

at Leeds Beckett University, UK, says the project is 鈥渆xciting鈥�, but warns that in-home surveys will still be crucial before starting any retrofit work. 鈥淗omes have been messed around with so many times. So identical homes could be completely different,鈥� he says. 鈥淲hile this fast, rapid stuff is great to accelerate progress and momentum, it cannot and should not replace really good-quality surveys in advance of doing the work.鈥�

at Nottingham Trent University, UK, says the neighbourhood data gathered by the BESS vehicles could prove useful when planning local power grid upgrades or climate resilience projects. But data should be captured mindfully, she says. 鈥淲hat is the minimum amount of data we need to make a good decision?鈥� she says. 鈥淏ecause that minimises the environmental impact of storing that data.鈥�