Quick Answer
If pure water's freezing point rose to around room temperature while other properties stayed similar, exposed water would freeze across much of Earth's surface. Oceans would not necessarily become a single solid block because salinity, pressure, geothermal heat and phase behavior matter. Living cells would face an extreme problem because most biological chemistry occurs in water, and freezing can damage cellular structures.
Water is unusual enough that changing its phase-change temperature would affect almost every Earth system. Clouds, rivers, oceans, cells and industrial processes all depend on the fact that water is normally liquid over a broad range of everyday temperatures.
Puddles would freeze first
At ordinary room temperatures, exposed freshwater would become ice. Rivers and lakes would begin changing rapidly, although the exact rate would depend on heat transfer, depth, impurities and the assumed new freezing behavior.
The oceans are more complicated
Seawater does not freeze at exactly the same temperature as pure water because dissolved salts lower its freezing point. Pressure also affects phase boundaries. If the hypothetical raises the freezing point of water itself, the oceans would still respond according to their salinity and pressure profile rather than instantly turning into one uniform block.
Life would be hit hardest
Cells contain large amounts of water. Freezing can form ice crystals that damage membranes and other structures, which is why biological tissues normally need specialized adaptations or cryoprotective conditions to survive freezing. A room-temperature freezing point would make ordinary terrestrial biology extraordinarily difficult to maintain.
Weather changes
The hydrological cycle would be transformed. Liquid evaporation, cloud formation, precipitation and snow or ice storage would operate under a completely different phase diagram. Rain could become an unusual phenomenon, while ice and vapor could dominate different parts of the cycle.
SpeculativeThis scenario changes a fundamental material property, so many secondary properties cannot be assumed to remain exactly the same. A physically complete model would need to specify how vapor pressure, heat capacity, density and latent heat change along with the freezing point.
Human infrastructure
Pipes, cooling systems, engines, food production and chemical industries all rely on water staying liquid in particular temperature ranges. The economic shock would begin almost immediately because enormous parts of modern infrastructure are designed around ordinary water phase behavior.
The bottom line
Raising water's freezing point to room temperature would not just give the world more ice. It would change the physical environment in which cells, weather and civilization operate. The biological consequences would likely be among the most severe because life itself is built around water remaining liquid.
A note on our approach: Every article on WhatIfLab separates what current science establishes from what remains genuinely speculative. Where we cite a figure or finding, it reflects published, mainstream research at the time of writing — not a prediction dressed up as fact.