Over the past decade, there has been a collective rally around the world to reach net-zero emissions by midcentury. But growing evidence suggests that reaching net zero within this timeframe is no longer enough to ensure delivery of the Paris Agreement’s 1.5 degrees C (2.7 degrees F) goal to prevent the ever-worsening consequences of climate change. Rather, it is now clear that the world needs to go farther.Last month, the UN Environment Programme issued a stark warning that the world will exceed 1.5 degrees C of warming, at least temporarily. This means more intense weather extremes, glacier melt, fires and sea-level rise, translating to higher costs and risks to people’s homes, health and livelihoods.To bring temperature back down to safer levels this century, the world will need to go ‘net negative,’ by making deep emissions cuts and removing more carbon dioxide (CO2) than is being emitted into the atmosphere.While net zero has been in global discourse for years, the concept of reaching and sustaining net-negative emissions to draw down stores of CO2 concentrated in the atmosphere is less well known. Here, we explain what net negative is, why it is needed and what it will take to achieve it.What Does Net Negative Mean?Reaching net zero in any given year involves reducing annual greenhouse gas (GHG) emissions by as much as possible with technologies and approaches that are available — for example, by replacing fossil fuels with clean energy. Any remaining — or residual — emissions are then balanced out by removing an equivalent amount of CO2 from the atmosphere. At net negative, however, annual carbon dioxide removals surpass those residual emissions, resulting in an overall decline in the total amount of CO2 that has accumulated in the atmosphere, which lowers the global temperature. Most policy discussions today focus on net negative specifically with regard to CO2 emissions, rather than other GHG emissions. This is because, without removal, CO2 persists in the atmosphere for centuries to millennia, whereas other GHGs like methane, despite being much more potent, have comparably shorter lifespans. Proposed approaches and technologies to remove non-CO2 emissions also face significant challenges that limit projected future potential.Critically, carbon removal within these net zero and net negative equations refers to deliberate, human-driven removals, rather than those that result from naturally occurring carbon fluxes that also influence the amount of CO2 stored in the atmosphere, such as ocean-atmosphere gas exchange.Will the World Breach the Paris Agreement’s 1.5 Degree C Goal?In 2024, for the first year on record, the world’s average annual temperature exceeded 1.5 degrees C above preindustrial levels. This alone does not mean that average global warming has exceeded 1.5 degrees C, as defined under the Paris Agreement. The Paris Agreement target is assessed by scientists using temperatures averaged over a 20- to 30-year period to smooth out year-to-year temperature fluctuations due to phenomena like El Niño. But, in the UN Environment Programme’s new Limiting Overshoot report, leading climate scientists have affirmed that the world will exceed an average peak warming of 1.5 degrees C over this multi-decade period, particularly since global GHG emissions continue to increase each year. This finding is underpinned by other literature that demonstrates that the world is likely already within this window. For instance, a 2025 study published in the journal Nature Climate Change analyzed previous, lower temperature thresholds and found that the first year that a given temperature level is exceeded has consistently also been part of the 20-year period when that same average level is transgressed. Another study published in the same journal used climate model simulations and reached a similar conclusion.However, exceeding an average warming of 1.5 degrees C over a multi-decade period is not synonymous with breaching the Paris Agreement’s long-term goal, which scientists say can still be achieved so long as temperatures are lowered before the end of the century. For example, the Intergovernmental Panel on Climate Change — the world’s foremost authority on climate science — has long considered emissions trajectories to be compatible with the Paris Agreement’s 1.5 degree C goal even if they involve a temporary overshoot. This is where net negative comes in.Why Are Net-Negative Emissions Needed to Lower Temperatures After Overshoot?There is strong scientific evidence that global temperatures will stop rising once net-zero CO2 emissions are reached (provided non-CO2 GHGs, like methane, also decline). The level at which warming stabilizes largely depends on total cumulative CO2 emissions stored in the atmosphere up to that point, or the atmospheric concentration of CO2. This is one reason why it is important to reach net zero as quickly as possible: The more we emit before getting there, the higher atmospheric CO2 concentrations and consequent peak warming will be — and the greater the damage to people and nature.But net zero only stops warming from continuing to rise — it doesn’t reverse warming that has already occurred. As average global temperature rise surpasses 1.5 degrees C, the world will need to lower the concentration of CO2 emissions in the atmosphere via a period of sustained net-negative CO2 emissions to get back to that threshold or below.At the same time, reducing non-CO2 emissions like methane from agriculture, waste and remaining fossil fuel use remains critical. If more residual non-CO2 emissions remain in the atmosphere, considerably more carbon removal will be required to achieve the same warming declines, particularly given the potency of these emissions.Critically, after net negative brings atmospheric CO2 concentration back down to levels of warming consistent with 1.5 degrees C of warming, transitioning back to net zero would keep temperatures steady.Have Countries Agreed to Reach Net-Negative Emissions?The Paris Agreement does not explicitly mention net-negative emissions. It does, however, commit countries to holding warming to well below 2 degrees C (3.6 degrees F) above preindustrial levels and pursuing efforts to limit warming to 1.5 degrees C.Limiting warming to 1.5 degrees C by the end of the century, in particular, has been discussed as an enduring moral, legal and ethical imperative for signatories of the Paris Agreement — nearly every country in the world. For instance, a 2025 advisory opinion from the International Court of Justice determined that 1.5 degrees C is the ‘primary temperature goal’ of the Paris Agreement, which was further affirmed by a 2026 UN General Assembly resolution.Given the now certainty that the world will — at least temporarily — exceed an average warming of 1.5 degrees C above preindustrial levels over a multi-decade period, we know net-negative CO2 emissions will be needed to lower warming back to that level this century.So, while net negative is not explicitly mentioned in the Paris Agreement, it should increasingly be understood as a logical prerequisite for achieving what countries have already agreed to.What Economywide Transformations Will Be Needed?The good news is that reaching net-negative emissions does not require reinventing the wheel. Instead, it requires the world to accelerate many of the same actions known to be needed.First and foremost, immediate and deep emissions reductions must remain the top priority. Specifically, to reach net zero as soon as possible and halt further warming from occurring, the world must rapidly slash emissions across power, buildings, industry, transport, forests and land, and food and agriculture. Rapid emission cuts will reduce the peak level of warming that the world experiences and, in doing so, minimize potential for crossing often irreversible climate tipping points like ice sheet collapse.Investing in emissions reductions has also been shown to deliver simultaneous improvements in growth, affordability, jobs, health, quality of life and resilience to natural disasters and economic shocks. It also remains far more cost effective than addressing the costs of worsening climate impacts later.At the same time, the world also needs to deploy both natural and technological carbon dioxide removal approaches at unprecedented scale to reach net negative. But critically, carbon removal is not a limitless resource, available at any scale to compensate for a large magnitude of residual emissions or ever-growing quantity of emissions already in the atmosphere.These limitations make rapidly cutting emissions in the near term even more urgent. The closer residual emissions can be pushed toward zero, the less carbon removal will be needed to reach net zero, preserving the limited quantities that are projected to be available for unlocking net negative. Meanwhile, less CO2 accumulated in the atmosphere in the first place means less total carbon removal will be needed to reach net negative. Rapid, near-term emissions reductions will also be far less costly than continuing to emit and trying to reverse course later. What Constraints Limit Maximum Potential Carbon Removal?Both natural and more novel technological carbon removal approaches today face real constraints that limit estimates of their maximum technical potential. For natural approaches like reforestation and ecosystem restoration, a key constraint is land. Land is finite, and, particularly as demand for food, animal feed, fiber and fuel increases, it faces increasing competition that limits how much can be sustainably dedicated to removing carbon. Additionally, climate change itself is already weakening some of the world’s natural carbon sinks, primarily as rising temperatures and drought cause more trees to die. These intensifying impacts will also limit how much carbon restored ecosystems can absorb and threaten their ability to keep it stored.For this reason, some experts have called for a like-for-like principle in which emissions with long lifespans in the atmosphere (e.g., CO2) are compensated for by particularly durable carbon removal and storage approaches (e.g., direct air capture with geologic sequestration). Yet the costs of these more nascent approaches remain high — and deployment levels today still remain very low — limiting estimated technical potential.Both natural and technological approaches will need to scale significantly. But, because carbon removal provides a global public good, there may be insufficient incentives for governments, companies or individuals to pay for what’s needed. While critical, public funding alone is unlikely to fill this gap, particularly given competing demands on limited public resources. Carefully crafted policies, regulations, fiscal incentives and markets will therefore be critical to mobilizing an appropriate mix of public and private finance for carbon removal.When Must the World Reach Net Negative — and How Much Carbon Removal Will it Take?The deadline for reaching net negative depends on how much emissions grow before peaking — and how much higher warming climbs as a result — as well as how quickly emissions fall to net zero thereafter. New pathways profiled in the UN Environment Programme’s Limiting Overshoot report demonstrate how bringing warming back to 1.5 degrees C this century remains possible and can help make sense of what’s needed after net zero.Specifically, these pathways show that, given delays in global emissions reductions and the warming trajectory that’s locked in, the world is already likely to experience a peak warming of at least 1.6 degrees C to 1.8 degrees C (2.9 degrees F to 3.2 degrees F). At the same time, given limitations to total carbon removal projected to be available, these same pathways capable of returning warming to 1.5 degrees C by 2100 or earlier peak at no more than about 1.8 degrees C to 1.9 degrees C (3.2 degrees F to 3.4 degrees F).So, if the highest peak from which models can still return warming to 1.5 degrees C this century is 1.8 degrees C to 1.9 degrees C, and we’ve already locked in an overshoot of at least 1.6 degrees C to 1.8 degrees C of warming, the margin for error has all but disappeared. How fast the world reaches net zero over the next decades to stop continued warming is what will decide whether a return to 1.5 degrees C this century, facilitated by a period of net-negative emissions, stays possible at all. How Much Carbon Removal Is Needed to Lower Temperatures Back to 1.5 Degrees C?UN Environment Programme authors estimate that each 0.1 degree C (0.2 degree F) of temperature decline will require removing roughly 220 gigatons of carbon dioxide (GtCO2) from the atmosphere. By this measure, reversing a peak of 1.8 degrees C to 1.9 degrees C back to 1.5 degrees C would require removing roughly 660 GtCO2 to 880 GtCO2 cumulatively over the rest of the century, equivalent to 50 to 67 times the size of China’s annual emissions today. And, some research suggests even greater removals may be needed, given uncertainties still surrounding the precise long-term climate response to declining atmospheric CO2 concentrations.Still, removals of this magnitude push limits on what is projected to be feasible in the literature — particularly given that today’s carbon removal levels are just over 2 GtCO2 per year, compared to the nearly 58 GtCO2e per year the world emits today. This underscores why scientists have emphasized that we’ll likely only be able to reverse a few tenths of a degree C this century at best with carbon removal projected to be available. Are Any Countries Preparing to Achieve Net Negative?A small but growing number of countries are already exploring what a net-negative future could look like.One of the clearest signals is from the Group of Negative Emitters — a coalition of countries including Denmark, Ethiopia, Finland, Kenya, the Netherlands, Panama, Suriname and Sweden — committed to achieving and maintaining net-negative emissions. Some countries, including Bhutan, Panama and Suriname — report that they’ve already reached a state of national net-negative emissions in which more carbon is absorbed than emitted each year. Ensuring that this state is maintained over time — and that removals are stored durably, particularly amid intensifying climate impacts — will be critical.Achieving domestic net-negative emissions in other, higher-emitting economies will require robust policy ecosystems, including demand-side policies such as carbon dioxide removal purchase mandates and government procurements, supply-side policies such as funding for research, development and deployment, grants and investment tax credits, and broader governance frameworks like sustainability safeguards and measurement, reporting and verification standards. Market-based mechanisms, such as carbon prices and the integration of high-quality removals into compliance carbon markets, will also be key to mobilizing private investment alongside public funds.Looking AheadThe growing conversation around 1.5 degrees C overshoot and net-negative emissions reflects a shift in how scientists and policymakers are thinking about the climate challenge.For years, reaching net-zero CO2 emissions by midcentury was understood as the key benchmark needed to deliver the Paris Agreement’s 1.5 degrees C goal, but we now know that will not be enough. Meeting this long-term goal will now require the world to peak emissions as soon as possible, reach net zero and thereafter achieve net-negative emissions to actually lower the amount of CO2 in the atmosphere.Fortunately, we know exactly how to get there and many of the necessary actions strengthen economies and improve people’s lives. Countries still need to rapidly slash emissions across every sector of the economy by phasing out coal power, halting deforestation, scaling up zero-carbon power and electric vehicles and more. At the same time, the world must scale up carbon dioxide removal responsibly and sustainably at unprecedented rates.The faster emissions fall today, the lower peak warming will be, and the more feasible it becomes to limit the magnitude and duration of overshoot beyond 1.5 degrees C. Conversely, delaying emissions reductions now would increase future dependence on large-scale carbon removal and deepen the risks faced by both people and nature.In this sense, the path toward net negative begins with the same actions the world already knows it must take today — only with greater urgency than ever.