The world’s biggest fossil fuel firms are quietly planning scores of “carbon bomb” oil and gas projects that would drive the climate past internationally agreed temperature limits with catastrophic global impacts, a Guardian investigation shows.

The exclusive data shows these firms are in effect placing multibillion-dollar bets against humanity halting global heating. Their huge investments in new fossil fuel production could pay off only if countries fail to rapidly slash carbon emissions, which scientists say is vital.

The oil and gas industry is extremely volatile but extraordinarily profitable, particularly when prices are high, as they are at present. ExxonMobil, Shell, BP and Chevron have made almost $2tn in profits in the past three decades, while recent price rises led BP’s boss to describe the company as a “cash machine”.

The lure of colossal payouts in the years to come appears to be irresistible to the oil companies, despite the world’s climate scientists stating in February that further delay in cutting fossil fuel use would mean missing our last chance “to secure a liveable and sustainable future for all”. As the UN secretary general, António Guterres, warned world leaders in April: “Our addiction to fossil fuels is killing us.”

In 1958, a combine carrying a full load of freshly harvested crops might weigh 8,800 pounds (4000 kg). Today, a fully loaded combine can clock in at 80,000 pounds (36,000 kg).

The story of increasingly large farm vehicles isn't necessarily bad. The invention of these huge machines — along with advances like new fertilizers and genetically modified crops — mean that today's farmers can grow far more food than ever before. But there's reason to worry that equipment manufacturers have begun pushing the envelope too far.

In a paper published Monday in the peer-reviewed journal PNAS, researchers show that farm equipment has grown so large that its heft can damage the soil that lies more than 20 inches (0.5 m) below the surface.

"Ironically, highly efficient tractors and harvesters may hamper progress toward increasing food production... due to the unintended risk of subsoil compaction," the authors write.